rock types in the prairies in North america, are they going to be basically the same as rock types from prairies overseas? (both from landlocked areas, not close to water, or volcanoes, but on different continents) tl;dr: does world location affect rocks (world location besides water, volcanoes, that stuff) this doesnt make much sense does it -_-;
Hey, if you're still taking questions; What exactly is a moss aquamarine? Where can I go to find some answers. It mostly shows up in etsy and Indian bead wholesellers. I love the color and inclusions but don't want to pay for glass or resin. Thanks!
Aquamarine in general is a variety of the mineral beryl (emeralds are also another variety of beryl, incidentally. chrysoberyl is, however, entirely unrelated). As far as telling it apart from glass or resin, the easiest way is hardness - beryl will scratch glass, glass will never scratch beryl. Past that, though, I dunno how much I can help you. I'm more on the science side of things than the gem show side, and I'm not really the person to ask about checking the legitimacy of online sellers.
PM me? I have a bit of lapidary interest and might at least know how to start looking into whatever particular place you're looking at.
If you still need answers can PM me. I don't know anything but Monster ( a member of the family ) does this kind of thing for a living. He's currently taking over the job of curator for a billion dollar gem&mineral collection, including buying and selling for it, so probly knows a little about it. He's really crappy about keeping his site up to date (probably because he spends his time digging/buying/selling mineral specimens), but he does know his rocks.
Been sitting on this one for a while, because it is an excellent question, which unfortunately for me means I have to do a lot of writing. The basic answer is, no, world location beyond geologic setting does not affect rocks. There's not a set of "rocks of the Americas" that are more or less distinct from "rocks of Asia," it's the same kinds of rock in both places. However, the rocks under grasslands in North America could still be wildly different from the rocks under a grassland in Asia, for a couple reasons. The first is that what the area looks like now matters a lot less than what it looked like when those rocks were forming. Let's say we're looking at a bit of landlocked grassland with sedimentary bedrock (sedimentary because that's the kind of rock that is going to be influenced by water and habitat). Let's say the rock there is 20 million years old, and 20 million years ago that area was underwater, just off the coast. If you want to look for a place that has similar rocks, you'd be better off going offshore than going to other grasslands or to other landlocked areas. Or, if you know the geologic history of other areas, you could go to other places that were once just offshore at some point, whether those places are still just offshore, or landlocked forests, or have been outright uplifted into a mountain chain since then. The same applies to volcanoes; there are no volcanoes in Wisconsin nowadays, but there were a couple billion years ago, and the rocks they made are still around. (I mention wisconsin in particular, because the @kmoss is playing the Hero of Space in my SBURB game, and they mentioned their character was from wisconsin, so I had to go hunting around for a suitable Forge). The second is that you can get grasslands that look pretty much the same biologically in areas that are quite different geologically, and similarly you can have areas that are far away from water and volcanoes that are in very different geological situations (or that are in similar situations now but with very different geologic histories, as per the first point). Serious props to you for starting to pin down the idea of geologic setting with regards to your comments about water and volcanoes, but the biggest factor in geologic setting is going to be plate tectonics, especially when you're dealing with igneous or metamorphic rocks. Sedimentary rocks are much more closely tied to biome/habitat, and especially to what water is doing, but tectonics are still a huge factor, and a grassland coming right off of high mountains is going to get different sedimentary rocks than a grassland where all the sediment has traveled miles and miles and miles across flat ground in meandering rivers, even if both are fairly similar habitat and fairly similar distances from water and volcanoes. That said, there's also all sorts of exciting feedback loops between the biology and geology of an area, with one influencing the other influencing the first, which then influences the second differently and then... Thirdly, there's not just one kind of rock, or even a nice simple set of kinds of rocks, under the North American prairies. More like. Well.
Is why Monster travels all over the country to dig for rocks. If they was all the same he could stay in one cave.
@Wiwaxia That is really interesting and cool oh boy. :D I'm glad I asked a good question, that was really fun to read. The bits about history of a place was very interesting too!
geology infodumping from the skype chat, copied here at @Ducks request messages from other people redacted unless they were interacting with the infodump Spoiler: long [7:35:25 PM] Wiwaxia foliosa: HI I JUST GOT BACK FROM DINNER AND I HEARD SOMEONE SAID ROCKS [7:41:37 PM] Hatchback: HELLO YES CAN YOU TELL ME THE GOOD WORD [7:44:43 PM] Wiwaxia foliosa: WHAT GOOD WORD WOULD YOU LIKE TO KNOW? [7:44:57 PM] Wiwaxia foliosa: AKA GIVE ME A POINT TO START INFODUMPING [7:47:49 PM] a big fat lizard [Avery]: update: my stew is a bit more like soup but is very good [7:48:04 PM] a big fat lizard [Avery]: addition: there are no rocks in my stew [7:48:13 PM] Wiwaxia foliosa: not even halite? [7:48:24 PM] Wiwaxia foliosa: although that's technically a mineral [7:49:00 PM] Hatchback: HOW DO THEY FORM [7:49:05 PM] Hatchback: LIKE THERE'S SO MANYPRETTY KINDS [7:49:12 PM] Hatchback: i'm moh or less interested in everything tho [7:49:28 PM] Hatchback: so that's a hard question [7:49:34 PM] Wiwaxia foliosa: nicely done [7:49:53 PM] Hatchback: Should I scale it back? [7:50:11 PM] Wiwaxia foliosa: are you sure you want to start a rock pun war with me? [7:50:16 PM] Wiwaxia foliosa: someone might get chert [7:50:45 PM] Hatchback: yeah, let's not make this a rocky relationship [7:50:56 PM] Hatchback: you're a diamond but I'm not as good under pressure [7:51:22 PM] Wiwaxia foliosa: keep everything gneiss, got it [7:51:46 PM] a big fat lizard [Avery]: oh my god you guys, rock pun wars happen so often XD [7:51:52 PM] Hatchback: I am not surprised. [7:51:58 PM] Wiwaxia foliosa: ANYWAYS [7:52:03 PM] Wiwaxia foliosa: rock formation! [7:52:22 PM] Wiwaxia foliosa: starting with igneous, probably [7:52:40 PM] Wiwaxia foliosa: because that's a good place to start [7:52:45 PM] Hatchback: excellent [7:52:47 PM] Wiwaxia foliosa: oh but first off [7:53:14 PM] Wiwaxia foliosa: facts that your science classes probably failed you on: the mantle is solid [7:53:17 PM] Wiwaxia foliosa: not liquid [7:53:20 PM] Wiwaxia foliosa: solid [7:53:41 PM] Hatchback: ... yeah I didn't know that I thought it was lava [7:53:53 PM] Hatchback: wait. magma. [7:53:55 PM] Wiwaxia foliosa: i am eternally grumpy that most earth science textbooks, websites, and displays get this wrong [7:54:09 PM] Hatchback: ... wix did you go to school of rock or something? [7:54:39 PM] Wiwaxia foliosa: i mean i'm literally most of the way through a geology major [7:54:41 PM] Wiwaxia foliosa: so yes [7:55:07 PM] Wiwaxia foliosa: anyways mantle = solid [7:55:17 PM] Wiwaxia foliosa: because of pressure, mostly [7:55:41 PM] Wiwaxia foliosa: it's at temperatures that would be molten at surface pressure, but it is very much not at surface pressure [7:55:57 PM] Wiwaxia foliosa: so where you get magma from [7:56:12 PM] Wiwaxia foliosa: is either something is removing some of that pressure [7:57:02 PM] Wiwaxia foliosa: which is what happens at mid ocean ridges - the crust is pulled apart so there's less pressure on the rock immediately below it, so that rock starts melting [7:57:12 PM] Wiwaxia foliosa: and then the molten rock is less dense, so it rises [7:57:37 PM] Wiwaxia foliosa: and as it rises, it creates an area of low pressure behind it, so some more rock melts, etc. [7:57:59 PM] Wes: Cool [7:58:33 PM] Wiwaxia foliosa: there's a couple other ways to get magma [7:59:00 PM] Wiwaxia foliosa: one is if something like water is added to the rock which drops its melting point at that temperature [7:59:12 PM] Wiwaxia foliosa: and another is mantle hot spots [7:59:39 PM] Wiwaxia foliosa: where you have really hot rock rising directly off the bottom of the mantle [7:59:59 PM] Hatchback: ... neat [8:00:03 PM] Wiwaxia foliosa: so when it gets close to the surface, it's still super fucking hot [8:00:03 PM] Wes: Oo [8:00:13 PM] Wes: (Hawaii?) [8:00:23 PM] Wiwaxia foliosa: and there's a lot less pressure, because all that rock that was pushing down on it is below it [8:00:34 PM] Wiwaxia foliosa: so it's hot enough to melt even at those pressures [8:00:36 PM] Wiwaxia foliosa: yep! [8:00:46 PM] Wiwaxia foliosa: also the galapogos, yellowstone [8:00:52 PM] Wiwaxia foliosa: iceland [8:01:20 PM] Wiwaxia foliosa: iceland's kinda a special case because it's a mantle hotspot sitting directly under a mid-ocean ridge [8:01:47 PM] Hatchback: ooh, on the [8:01:51 PM] Hatchback: [dramatic pause] [8:01:56 PM] Hatchback: RING OF FIRE? [8:02:00 PM] Wiwaxia foliosa: there's others around but i can't think of them off the top of my head [8:02:05 PM] Wiwaxia foliosa: nope, actually! [8:02:07 PM] Wiwaxia foliosa: the [8:02:13 PM] Wiwaxia foliosa: [dramatic pause] [8:02:17 PM] Wiwaxia foliosa: RING OF FIRE [8:02:23 PM] Wiwaxia foliosa: is a Pacific ocean thing [8:02:35 PM] Keleviel: And when you go down down down [8:02:37 PM] michinyo || Brittany: I'm applying to be a judge for a competition I was in last year, they asked for samples of voice work and art work [8:02:45 PM] Keleviel: The flames leapt higher [8:02:47 PM] michinyo || Brittany: then asked me to judge a video as if it were an entry [8:02:51 PM] Keleviel: And it burns burns burns [8:02:55 PM] Wiwaxia foliosa: actually, yes that exactly, kel [8:03:39 PM] Wiwaxia foliosa: the Ring of Fire happens because the pacific plate is subducting under various other places all around it's edges [8:03:48 PM] Wiwaxia foliosa: and subduction leads to vulcanism [8:03:59 PM] Wiwaxia foliosa: because of that aforementioned thing with the water michinyo || Brittany [8:04:17 PM] Wiwaxia foliosa: there's a number of minerals that contain water in their crystal structures [8:04:17 PM] Keleviel: Um no [8:04:22 PM] Hatchback: I saw a really cool IMAX about it, but that was years ago [8:04:27 PM] Keleviel: It happens because love is a burning thing [8:04:36 PM] Keleviel: And it makes a fiery ring [8:04:55 PM] Wiwaxia foliosa: and when those get to a certain temperature, they decompose and release the water [8:05:21 PM] Wiwaxia foliosa: so when the subducting plate hits the depth that is that temperature, suddenly there's a bunch of water [8:05:33 PM] Wiwaxia foliosa: water drops the melting point, shit starts to melt [8:05:36 PM] Wiwaxia foliosa: shit rises [8:05:41 PM] Wiwaxia foliosa: boom volcanoes [8:05:46 PM] Wiwaxia foliosa: thus the cascades [8:05:47 PM] Wiwaxia foliosa: the andes [8:05:50 PM] Wiwaxia foliosa: japan [8:06:00 PM] Wiwaxia foliosa: lots of south pacific volcanic islands [8:06:03 PM] Wes: Japan is gr8 [8:06:30 PM] Wiwaxia foliosa: also worth noting that when rock melts it doesn't go all at once [8:06:41 PM] Hatchback: asst. atolls and such [8:06:51 PM] Wiwaxia foliosa: those drawings with big tanks of lava under a volcano? [8:06:59 PM] Wiwaxia foliosa: fake fake fakey fake [8:06:59 PM] Hatchback: not accurate? [8:07:51 PM] Wiwaxia foliosa: what's actually going on is that the edges and corners of crystals start to melt [8:07:51 PM] a big fat lizard [Avery]: HOW WILL I BUILD MY VILLAIN LAIR IF I DONT HAVE A LAVA LAKE [8:08:32 PM] Wiwaxia foliosa: so you've got solid rock that's holding liquid in pore spaces [8:08:45 PM] Wiwaxia foliosa: like a sponge, or wet sand [8:09:04 PM] a big fat lizard [Avery]: pores... volcanoes really are the earths zits [8:09:12 PM] Wiwaxia foliosa: or actually a lot more accurately, like soaked porus concrete [8:09:50 PM] Wiwaxia foliosa: following so far? [8:10:59 PM] Hatchback: Yes! [8:11:54 PM] Wiwaxia foliosa: okay gotta relocate, brb [8:15:48 PM] Wiwaxia foliosa: okay, back [8:16:18 PM] Wiwaxia foliosa: so! [8:16:44 PM] Wiwaxia foliosa: you've got this nice melted magma sitting in the pore spaces of some solid rock [8:17:36 PM] Wiwaxia foliosa: from there it can rise and force itself into the country rock and cool underground as an intrusive igneous sill or dike [8:18:05 PM] Wiwaxia foliosa: or erupt all the way out onto the surface as an extrusive igneous eruption [8:19:42 PM] Wiwaxia foliosa: either way, you are going to start getting minerals crystalizing out of this liquid [8:20:38 PM] Hatchback: :D [8:21:09 PM] Wiwaxia foliosa: so there's an idealized series of the minerals that crystalize first, when the liquid is hottest, and when cool subsequently, and then which cool last [8:21:19 PM] Wiwaxia foliosa: called Bowen's Reaction Series [8:21:28 PM] Wiwaxia foliosa: i'll grab a diagram, one sec [8:23:02 PM] Wiwaxia foliosa: [8:24:36 PM] Hatchback: This is pretty interesting! [8:25:11 PM] Wiwaxia foliosa: okay so there's two places i can go from here [8:25:34 PM] Wiwaxia foliosa: do you wanna talk about what's going on with crystal structure that's making that shit happen? [8:26:00 PM] Wiwaxia foliosa: or i could yak about magma chemistry and complications with that idealized model [8:28:37 PM] Wiwaxia foliosa: here's a picture of the reaction series with photos of all the minerals [8:33:52 PM] Hatchback: Crystal structure1 [8:35:10 PM] Wiwaxia foliosa: eeexcelent [8:35:20 PM] Wiwaxia foliosa: i love crystal structure shit [8:35:22 PM] Wiwaxia foliosa: so! [8:35:43 PM] Wiwaxia foliosa: all those minerals on the diagram belong to the same general family of minerals [8:36:07 PM] Maddie: oh I didn't know you were doing a geology major [8:36:10 PM] Maddie: and yet it makes sense [8:36:18 PM] Maddie: i'm now wondering how much geology trivia is in the SBURB game [8:36:41 PM] Wiwaxia foliosa: all of moss's grist is sedementological [8:36:50 PM] Wiwaxia foliosa: several of myrtha's grists are [8:37:06 PM] Maddie: ummm I think her grist types are [8:37:16 PM] Maddie: ...indigo and woad, which are dyes that I think are derived from plants [8:37:17 PM] Wiwaxia foliosa: well, geological, not sedementological [8:37:18 PM] Maddie: cobalt? [8:37:23 PM] Maddie: though that's an element [8:37:27 PM] Wiwaxia foliosa: not ones you've run across yet! [8:37:30 PM] Maddie: ohhh [8:37:41 PM] Maddie: consider me intrigued [8:37:57 PM] Wiwaxia foliosa: :D [8:38:07 PM] Wiwaxia foliosa: so yes, those are all silicate minerals [8:38:21 PM] Maddie: ilma's got bismuth all over [8:38:24 PM] Wiwaxia foliosa: as is the vast majority of earth's mantle and crust [8:38:28 PM] Maddie: neat! [8:38:53 PM] Wiwaxia foliosa: which means that they all contain SiO4 ions [8:39:31 PM] Maddie: I see [8:39:40 PM] Maddie: what about leon and lemi? [8:40:09 PM] Wiwaxia foliosa: oh, i meant going back to the bowen's reaction series [8:40:19 PM] Maddie: o [8:40:26 PM] Wiwaxia foliosa: i don't think they have that much geological [8:40:30 PM] Maddie: mm [8:40:45 PM] Maddie: any steven universe mineral symbolism that you have spotted [8:40:56 PM] Wiwaxia foliosa: not all of myrtha's grist is silicate! [8:41:24 PM] Wiwaxia foliosa: a bit, with the quartzes [8:42:01 PM] Wiwaxia foliosa: also fun facts: lapis lazuli is a feldspathoid, which cannot coexist in a rock with quartz! [8:42:22 PM] Wiwaxia foliosa: although the reasons for that involve the other infodump about magma chemistry [8:42:33 PM] Maddie: huh [8:42:42 PM] Maddie: and i'm gonna guess that the stuff about peridotite is more or less accurate? [8:42:47 PM] Wiwaxia foliosa: yep! [8:43:08 PM] Wiwaxia foliosa: the mantle is indeed mostly peridotite [8:44:01 PM] Wiwaxia foliosa: or at least most of it [8:44:29 PM] Wiwaxia foliosa: the mantle directly under the continents is a bit weird, because it hasn't been circulating over and over and over like the rest of the mantle [8:44:39 PM] Maddie: why? [8:44:51 PM] Wiwaxia foliosa: and it's not depleted in certain elements and minerals that the rest of the mantle is [8:44:51 PM] Maddie: is it something like, too far from the core it gets too cool to do that much circulation? [8:44:54 PM] Maddie: wild guess [8:44:59 PM] Wiwaxia foliosa: nope! [8:45:14 PM] Wiwaxia foliosa: it's literally because it's right under the continents [8:45:17 PM] Maddie: oh [8:45:18 PM] Maddie: like [8:45:30 PM] Wiwaxia foliosa: so mantle circulation is a convection current kind of deal [8:45:37 PM] Maddie: huh! [8:45:59 PM] Wiwaxia foliosa: the mantle is solid, but it's hot enough to deform plastically, especially over long periods of time [8:46:14 PM] Wiwaxia foliosa: so you do get those convection cells like you'll see in hot soup [8:46:35 PM] Wiwaxia foliosa: with heat coming from the bottom, warming the rock or soup right at the bottom [8:46:54 PM] Wiwaxia foliosa: which then becomes less dense and then rises up to the surface [8:47:17 PM] Wiwaxia foliosa: displacing the rock or soup currently at that point on the surface and pushing it away sidways [8:47:40 PM] Wiwaxia foliosa: then it's pushed away in turn, and loses heat on the cooler surface [8:47:48 PM] Wiwaxia foliosa: becomes more dense and sinks [8:47:52 PM] Wiwaxia foliosa: hits the bottom [8:48:08 PM] Wiwaxia foliosa: is pulled into the space left behing by hot rising rock or soup [8:48:11 PM] Wiwaxia foliosa: and repeat [8:49:28 PM] Wiwaxia foliosa: the continental crust is like a very not-dense foam floating on top of the soup and being pushed around and mashed together and pulled apart by the convection cells [8:50:10 PM] Wiwaxia foliosa: the oceanic crust is not, it's best thought of as literally just the surface of the convection cell, not really that chemically distinct from the mantly [8:50:47 PM] Wiwaxia foliosa: meanwhile, the continents are so light that anything that happens there is basically gonna stay there, and not get recirculated into the rest of the pot [8:51:29 PM] Wiwaxia foliosa: so they've accumulated a bunch of less dense shit and various weird isotopes that have been lost in the rest of the soup that just keeps going round and round and round [8:52:40 PM] Wiwaxia foliosa: and because you can't run an oceanic plate all the way along the bottom of a continent, that means there's this area of the mantle that's kind of protected from all that circulation [8:52:54 PM] Wiwaxia foliosa: so it's thought to be closer to earth's original mantle composition [8:53:22 PM] Wiwaxia foliosa: and it has a bunch of those weird isotopes that all the rest of the mantle has lost [8:53:43 PM] Wiwaxia foliosa: it is also, incidentally, where diamonds come from, although i don't know if that's related or not [8:53:58 PM] Wiwaxia foliosa: if all that makes sense? [8:54:17 PM] Hatchback: It does! [8:54:27 PM] Maddie: yeah! [8:54:58 PM] Maddie: actually that kind of explains something that I was kind of curious about [8:55:03 PM] Maddie: which was [8:56:04 PM] Maddie: if the tectonic plates are covering the surface of the planet, then how do they move around, shouldn't they be basically stuck except for a bit of jostling [8:56:30 PM] Maddie: so how does something like Pangaea happen [8:56:42 PM] Maddie: and then un-happen [8:57:07 PM] Maddie: but if the continents aren't stuck to the oceanic plates [8:57:09 PM] Maddie: then it makes more sense [8:57:18 PM] Wiwaxia foliosa: yep! [8:58:49 PM] Wiwaxia foliosa: also, there's a lot of faults withing plates to alleviate the rest of that stress [8:59:26 PM] Wiwaxia foliosa: this is why mid-ocean-ridges are constantly jumping sideways [8:59:56 PM] Wiwaxia foliosa: those are transform faults to accomodate fitting that spreading around a sphere [9:00:34 PM] Wiwaxia foliosa: because when you're on the surface it's cooler and lower pressure so sometimes things fault rather than squishing smoothly like they do deeper in the crust or in the mantle [9:01:09 PM] Wiwaxia foliosa: also, if you look at a satellite veiw of asia, you cans literally see the entire continent bending around india [9:01:15 PM] Wiwaxia foliosa: as india fucking rams into it [9:01:49 PM] Maddie: heh [9:02:03 PM] Wiwaxia foliosa: so inland of the himalayas, there's actually spreading faults perpendicular to the line of the himalayas to accomodate the stretching and squishing that entails [9:02:41 PM] Wiwaxia foliosa: tectonics are fucking wild, especially once you start getting past the basics [9:03:07 PM] Wiwaxia foliosa: like this is all 100-level tectonics [9:03:21 PM] Wiwaxia foliosa: one of my profs does a special tectonics tutorial sometimes [9:03:40 PM | Edited 9:03:40 PM] Wiwaxia foliosa: so i'm hoping i can catch it for Even More Tectonics BS [9:05:56 PM] Wiwaxia foliosa: so, are you still interested in the silicate mineralogy infodump, hatchback? [9:20:35 PM] Hatchback: I am, yes! [9:20:55 PM] Hatchback: Sorry, I was getting my uniform together. This 101 lesson rocks [9:21:54 PM] Wiwaxia foliosa: :D [9:23:36 PM] Wiwaxia foliosa: okay, so. [9:23:55 PM] Wiwaxia foliosa: silicate rocks are rocks that contain the SiO4 4- ion [9:24:08 PM] Wiwaxia foliosa: incidentally, fuck your lack of subscript, skype [9:24:16 PM] Hatchback: I have to go to bed soon, but I will definitely go back and read it in the morning :3 [9:24:48 PM] Wiwaxia foliosa: there's a couple notable things about this ion, including that it is a tetrahedron [9:25:22 PM] Wiwaxia foliosa: and that the Si satisfies exactly half of each O's "want" for a positive charge [9:26:06 PM] Wiwaxia foliosa: which means that an O connected to 2 Si atoms will be neutrally charged and happy [9:26:27 PM] Wiwaxia foliosa: so these tetrahedrons can share corners pretty easily [9:26:39 PM] Wiwaxia foliosa: i'll grab a diagram real quick [9:27:55 PM] Wiwaxia foliosa: [9:28:01 PM] Wiwaxia foliosa: there's a nice one [9:28:20 PM] Wiwaxia foliosa: and it shows the different ways all these tetrahedra can link up [9:28:46 PM] Hatchback: (thank you for all this btw C: ) [9:29:00 PM] Wiwaxia foliosa: so if an O atom isn't shared between two tetrahedra it still "wants" a +1 charge to be neutral [9:29:09 PM] Wiwaxia foliosa: (np, i love infodumping about this) [9:29:14 PM] Wiwaxia foliosa: also, following so far? [9:29:23 PM] Hatchback: I am! Bed now, but tomorrow I will dig into this. [9:29:30 PM] Wiwaxia foliosa: gotcha gotcha [9:29:49 PM] Wiwaxia foliosa: wanted to check in, i don't know how much general chemistry knowledge is standard [9:31:16 PM] Wiwaxia foliosa: so the basic setup of silicate minerals is silica tetrahedra of some form of connectedness [9:31:43 PM] Wiwaxia foliosa: and then positive ions that cancel out the charges of all those un-shared O atoms [9:32:06 PM] Wiwaxia foliosa: so you can classify silicate minerals by how their silica tetrahedra line up
Spoiler: long part 2, damn you character limit [9:32:26 PM] Wiwaxia foliosa: on one end you have the orthosilicates or nesosilicates (neso=island) [9:32:42 PM] Wiwaxia foliosa: where the silica tetrahedra aren't linked up at all [9:32:46 PM] Wiwaxia foliosa: for instance, olivine [9:33:12 PM] Wiwaxia foliosa: which is (Fe,Mg)2SiO4 [9:33:59 PM] Wiwaxia foliosa: so you have two of Fe2+ and/or Mg2+ for each SiO4 4- [9:34:12 PM] Wiwaxia foliosa: neutral charge, everyone's happy [9:36:21 PM] Wiwaxia foliosa: also the crystal structure is nice and sane and you can actually see what the fuck is going on [9:36:22 PM] Wiwaxia foliosa: [9:36:40 PM] Wiwaxia foliosa: incidentally, olivine = peridot [9:37:12 PM] Wiwaxia foliosa: so those mantle peridotites are called that because they have a lot of olivine [9:38:34 PM] Wiwaxia foliosa: and the Si:O ratio is 1:4 [9:38:49 PM] Wiwaxia foliosa: next category is the single chain silicates, or single-chain inosilicates (ino=fiber) [9:39:37 PM] Wiwaxia foliosa: which if you scroll back up to the silica tetrahedra diagram is the one where each tetrahedron shares one corner with the one ahead of it and one with the one behind it [9:39:51 PM | Edited 9:40:05 PM] Wiwaxia foliosa: this is a mineral family called the pyroxenes [9:40:20 PM] Wiwaxia foliosa: (whoops, fucked that up) [9:41:33 PM] Wiwaxia foliosa: [9:42:01 PM] Wiwaxia foliosa: i guess you can kiiiiinda see what's going on with that crystal structure in terms of where the cations fit [9:42:02 PM] Wiwaxia foliosa: maybe? [9:42:21 PM] Wiwaxia foliosa: the grey is the silica tetrahedra chains [9:42:37 PM] Wiwaxia foliosa: anyways, there's a lot of those [9:43:36 PM] Wiwaxia foliosa: which we probably don't want to get into the specific names of [9:43:48 PM] Wiwaxia foliosa: jadeite, one of the two minerals called jade, is one though [9:43:59 PM] Wiwaxia foliosa: Si:O ratio is 1:3 now [9:44:11 PM] Wiwaxia foliosa: next is the double-chain inosilicates [9:44:53 PM] Wiwaxia foliosa: which is the same but every other tetrahedra shares a corner with the opposite chain [9:45:03 PM] Wiwaxia foliosa: so it looks like a chain of hexagons [9:45:14 PM] Wiwaxia foliosa: this is a mineral family called the amphiboles [9:45:20 PM] Wiwaxia foliosa: again, a shitload of them [9:45:36 PM] Wiwaxia foliosa: they are also a pain in the ass to distinguish from pyroxenes in hand sample [9:45:49 PM] Wiwaxia foliosa: the other mineral that gets called jade, nephrite, is one of these [9:46:19 PM] Wiwaxia foliosa: so is cummingtonite, if you are familiar with that [9:46:31 PM] Maddie: i wonder why all the s1 sailor moon villains were specifically named after green stones [9:46:41 PM] Maddie: because kunzite and zoicite are green as well, aren't they? [9:46:44 PM] Maddie: and beryl is, i think [9:47:11 PM] Maddie: oh no kunzite's pink [9:47:14 PM] Maddie: nvm then [9:48:08 PM] Maddie: i like the theory that naoko takeuchi once spent a traumatic few hours trapped under a mineral display case and that is why literally every villain except for Death Phantom and Galaxia are named related to geology or metallurgy [9:48:16 PM] Wiwaxia foliosa: all silicate minerals, tho [9:48:20 PM] Maddie: neat! [9:48:38 PM] Maddie: and ali and en, but their namepun is fairly obvious and they were anime-only [9:49:12 PM] Wiwaxia foliosa: zoesite is a sorosilicate, which is where you have pairs of SiO4 tetrahedra sharing a single corner like a kind of bowtie shape [9:49:50 PM] Wiwaxia foliosa: which i skipped because i forgot about it and also because none of them are really major rock-forming minerals in igneous rocks [9:50:55 PM] Wiwaxia foliosa: kunzite is a pyroxene and beryl is a cyclosilicate [9:51:42 PM] Wiwaxia foliosa: which is next, briefly [9:52:13 PM] Wiwaxia foliosa: anyways the amphiboles are also notable for all being hydrous [9:52:27 PM] Wiwaxia foliosa: they've got OH- ions in their crystal formulas [9:52:48 PM] Hatchback: (on my way back from the toilet later can you explain opals, too?) [9:52:56 PM] Hatchback: (they fascinate me) [9:53:17 PM] Wiwaxia foliosa: so they're one of the things responsible for releasing water in a subducting plate and causing melting and vulcanism that i was talking about earlier [9:53:32 PM] Wiwaxia foliosa: i believe i actually already explained opals on the forum! i can link you [9:53:34 PM] Wiwaxia foliosa: one sec [9:54:53 PM] Wiwaxia foliosa: https://kintsugi.seebs.net/threads/ask-a-geology-student.3042/#post-232150 [9:55:24 PM] Wiwaxia foliosa: https://kintsugi.seebs.net/threads/ask-a-geology-student.3042/page-2#post-232151 [9:56:03 PM] Wiwaxia foliosa: anyways, the Si:O ratio for amphiboles is 4:11 [9:56:14 PM] Wiwaxia foliosa: which you can see in all their chemical forumlas [9:56:27 PM] Maddie: ...i just took nighttime cold medicine so i am very tired and that emoticon is hilariou [9:56:39 PM] Wiwaxia foliosa: eg. Cummingtonite – Fe2Mg5Si8O22(OH)2 [9:56:45 PM] Wiwaxia foliosa: emoticon? [9:56:52 PM] Maddie: si:o [9:57:01 PM] Maddie: si and then a emoticon with :o [9:57:04 PM] Wiwaxia foliosa: please tell me that my Si colon O is not turning into emoticons [9:57:08 PM] Maddie: it is [9:57:08 PM] Wiwaxia foliosa: goddammit [9:57:13 PM] Maddie: foiled again [9:57:19 PM] Wiwaxia foliosa: fucking skype [9:57:29 PM] Wiwaxia foliosa: the hazards of having emoticons off, i guess [9:59:08 PM] Wiwaxia foliosa: so next up, briefly is cyclosilicates [9:59:11 PM] Wiwaxia foliosa: or ring silicates [9:59:20 PM] Wiwaxia foliosa: where the silica tetrahedra [9:59:22 PM] Wiwaxia foliosa: shockingly [9:59:29 PM] Wiwaxia foliosa: join up in a ring [9:59:49 PM] Wiwaxia foliosa: you can get four and six and other-number-tetrahedra rings [10:00:13 PM] Wiwaxia foliosa: these include beryl and tourmaline and a bunch of other pretty stuff that isn't really majorly rock-forming [10:00:39 PM] Wiwaxia foliosa: like you can have a beryl granite with lot of beryl, but you don't need beryl for anything [10:00:45 PM] Wiwaxia foliosa: it just shows up sometimes [10:00:48 PM] Wiwaxia foliosa: hi beryl [10:00:52 PM | Edited 10:00:56 PM] Wiwaxia foliosa: bye beryl [10:01:18 PM] Wiwaxia foliosa: moving on [10:01:42 PM] Wiwaxia foliosa: next is the phyllosilicates or sheet silicates (phyllo=leaf) [10:01:53 PM] Wiwaxia foliosa: aka ITS MICA TIME MOTHERFUCKERS [10:02:08 PM] Wiwaxia foliosa: DO YOU LIKE SHEETING BASAL CLEAVAGE TOO BAD YOU GOT IT [10:03:23 PM] Wiwaxia foliosa: all the silica tetrahedra are sharing all but one corner in a potentially infinite sheet of tesselating hexagonal rings [10:03:49 PM] Wiwaxia foliosa: this is why mica likes to come apart in sheets and really really does not want to come apart in other ways [10:04:23 PM] Wiwaxia foliosa: like you can fucking bend it, mica is nuts [10:04:54 PM] Wiwaxia foliosa: all your clay minerals go under the phyllosilicates, too [10:08:19 PM] Wiwaxia foliosa: the Si:O ratio is 4:10 [10:08:47 PM] Wiwaxia foliosa: although one or two of those Si atoms get replaced by lower-charged Al ions in a lot of things in this group [10:09:08 PM] Wiwaxia foliosa: meaning you need more or higher-charged other positive ions to be neutral [10:09:42 PM] Wiwaxia foliosa: these guys also have OH- ions or even full H2O molecules in the crystal structure [10:10:41 PM] Count Duckula: (will you copy paste this into your geology thread wax? I can't pay attention at the moment but it's super interesting) [10:13:44 PM] Wiwaxia foliosa: anyways, so with the sheet silicates, there's only one corner per tetrahedron left unconnected [10:14:03 PM] Wiwaxia foliosa: so the next and final group is the tectosilicates or framework silicates [10:14:13 PM | Edited 10:14:08 PM] Wiwaxia foliosa: there's a couple families here [10:14:24 PM] Wiwaxia foliosa: our good friend quartz [10:14:35 PM] Wiwaxia foliosa: which is just SiO2 [10:15:27 PM] Wiwaxia foliosa: literally nothing but silica tetrahedra joined at all the corners in this nice three-dimensional lattice that is fucking hell to represent in two dimensions coherently [10:16:14 PM] Wiwaxia foliosa: then you have feldspars [10:16:45 PM] Wiwaxia foliosa: where about one in four of those Si atoms is replaced with an Al atom [10:16:58 PM] Wiwaxia foliosa: again, Al is only 3+ to Si's 4+ [10:17:12 PM] Wiwaxia foliosa: so it can balance all the charges of all those oxygens [10:17:24 PM] Wiwaxia foliosa: so feldspars need to incorporate other positive ions [10:17:36 PM | Edited 10:19:53 PM] Wiwaxia foliosa: usually Ca2+, Na+ or K+ [10:18:41 PM | Edited 10:19:34 PM] Wiwaxia foliosa: you can get any proportion of Ca2+ and Na+ (and a corresponding proportion of Al3+ vs. Si4+) [10:18:55 PM] Wiwaxia foliosa: and those are the plagioclase feldspars [10:19:24 PM] Wiwaxia foliosa: and then you have orthoclase feldspar with K+ [10:20:28 PM] Wiwaxia foliosa: you can get a continuous range of proportions between K+ and Na+, but only at high temperatures [10:20:58 PM] Λ Maximise Salt: IT'S FUCKING FELDSPAR [10:21:21 PM] Wiwaxia foliosa: and if you're in the middle of that range, your feldspar will segregate into regions of K feldspar and regions of Na feldspar [10:21:23 PM] Wiwaxia foliosa: fun times [10:21:55 PM] Wiwaxia foliosa: there's also feldspathoids, which i mentioned before [10:22:32 PM] Wiwaxia foliosa: which have even higher Al:Si ratios, because they crystalize from magmas with unusually low Si [10:22:58 PM] Wiwaxia foliosa: again, they can't coexist with quartz, si-depleted magmas won't crystalize quartz [10:23:41 PM] Wiwaxia foliosa: and if they come in contact with quartz, they'll react to form feldspar until they're no longer in contact with the quartz (i.e. protected by a reaction rim of feldspar) [10:24:01 PM] Wiwaxia foliosa: un/fortunately for SU fans, malachite is not a feldspar [10:24:02 PM] Wiwaxia foliosa: sorry [10:25:36 PM] Wiwaxia foliosa: okay, copying down the bowen's reaction series image from above so you don't have to scroll all the way back up to it [10:25:37 PM] Wiwaxia foliosa: [10:25:56 PM] Wiwaxia foliosa: wow that order doesn't look at all familiar [10:26:54 PM] Wiwaxia foliosa: olivine, then pyroxene, then amphibole, then mica, then feldspar, then quartz [10:27:49 PM] Wiwaxia foliosa: decreasing temperature, increasing sharing of corners between silica tetrahedra [10:28:07 PM] Wiwaxia foliosa: (except for plagioclase, because plagioclase is doin its own thing kinda) [10:28:40 PM] Wiwaxia foliosa: or, said another way, silica tetrahedra like to link up more when its cooler [10:29:38 PM] Wiwaxia foliosa: or, said another way, metal cations like Fe2+ and Mg2+ crystalize at higher temperatures, so the rest of the molten rock becomes progressively more silica-rich as they remove themselves into solid crystals [10:30:33 PM] Wiwaxia foliosa: so that's how you can get a shitload of different minerals and a nice complicated rock from an originally homogenous liquid [10:31:12 PM] Wiwaxia foliosa: of course, like i said above, there's messiness with what the chemistry of that liquid actually contains [10:31:14 PM] Wiwaxia foliosa: :D [10:31:56 PM] Wiwaxia foliosa: incidentally, have an ordered list of susceptibility to weathering of various silicate mineral families [10:34:17 PM] Wiwaxia foliosa: [10:34:25 PM] Wiwaxia foliosa: there's some other shit in there [10:34:36 PM] Wiwaxia foliosa: but that should also look [10:34:42 PM] Wiwaxia foliosa: preeeeety familiar [10:35:25 PM] Wiwaxia foliosa: [10:36:19 PM] Wiwaxia foliosa: so lots of shared corners between silica tetrahedra helps prevent weathering [10:36:25 PM] Wiwaxia foliosa: or, said another way [10:36:51 PM] Wiwaxia foliosa: minerals are most stable when closer to the temperature they crystalized at [10:37:17 PM] Wiwaxia foliosa: so the minerals that crystalized at closest to surface temperatures should be the most stable on the surface [10:37:41 PM] Wiwaxia foliosa: (assuming crystalization from molten form rather than crystallization from dissolved form, of course)
hey-o! i have several rocks and minerals of uncertain variety, and I was wondering if you could ID any of them. I can do pics, and i can also run any tests you ask of me that dont require specific tools
