Hey geologists I need a bit of help with my worldbuilding.
So I'm adding dwarves to my setting but not your typical short stubby fleshy dudes. But rather short stubby rocky dudes. There are three types of dwarves upper crust, mid crust, and lower crust. They grow at different levels in the earth's crust and are made out of different rocks depending on what's available at that level. Like if they're closer to the surface they're made out of rocks and gems and such that naturally grow at that level.
Small issue though I have no idea what grows- forms? At those different levels farther or closer to the surface and I also don't know in what amounts. What's rare and what's common? I imagine diamonds don't grow in the same place as amethyst.
If you guys could help me out it would be much appreciated!
P.s. I did try googling it first but I couldn't find anything.
P.p.s. a visual representation like a rock map or something would be nice but is not required.
P.p.p.s. please don't be mean to me I'm not an expert on rocks I don't know exactly what to search for which is why I'm asking for help.
Hi! This is super interesting, So I want to expand of this a bit on my ideas!
my first thought would be to make the upper crust a sedimentary rock, I think the most visually interesting one could be a conglomerate
but I imagine it would be kind of interesting to have a variety of sedimentary rocks, like coquina, sandstone, limestone (with lots of fossils), etc.
The mid crust is usually an amphibolite (a metamorphic rock). These rocks characteristically have something called 'foliation' which is a fancy way of saying the minerals have a preferred orientation (it has layers).
and the deepest one being a peridotite (upper mantle) or a gneiss (lowest crust). Peridotite is what the mantle is made up of, its very pretty and Gneiss/granulite you might notice looks a lot like amphibolite. That is because they are both metamorphic rocks, but with increasing grade (gneiss/granulite being a higher grade than amphibolite).
If you were to use this system, sedimentary rocks gems/resources would be primarily coal/oil, iron (think rust and pyrite), lead (galena), and I think that is mostly it. However those are just, like, practical things. You could also include clay, as it is an important resource and fossils because those are only found in sedimentary rocks. You can also have a rare drop rate for things like diamonds, sapphires/rubies and gold. Sedimentary rocks are by nature, a rock made up of other rocks. Because of that, they can have just about anything in them, but sediments tend to become density separated, so high density things like the things I listed above can be found in sediments in a high enough amount to be mined!
For Amphibolites, they are just middle range metamorphic grade rocks, so some minerals that form in those kinds of conditions would be rubies and sapphires, emeralds, garnets, mica, talc, and some resources could be also iron (pyrite), copper (malachite/chalcopyrite), gold (gold), OH! and also graphite maybe? (the ores I have listed are typically formed from hydrothermal fluids because of that they can also be applied to the volcanism section listed later). To be clear though, there is amphibolite grade metamorphism (it indicates the pressure and temperature these rocks form at) and there is a rock specifically called an amphibolite. Do your best to try not to mix them up but if you need help you can always DM me.
For Peridotites, these is where we can bring in diamonds. Peridotites are typically made up of spinel (can be gem quality) olivine (I think the gem name for it is peridot), pyroxene, and garnet. However, diamonds are formed in the upper mantle, so this is where you could insert them.
If you did gneiss/granulite it would just be the same minerals as amphibolite.
You could also go a couple other directions though! So let us not exclude other ideas (but I will talk less about them).
you could just follow a metamorphic grade path shown below.
if you go this path you can just google things like "common minerals at such and such facies" and it should give you a decent list.
All of these ideas though have excluded igneous/volcanic rocks. If you wanted to include them, it might be worthwhile to add volcanic rocks like basalt, rhyolite, andesite, obsidian, tuff, pumice to surface/upper crust stuff and then add granite, diorite, and gabbro to middle crust. For lower crust, I would choose migmatites, as granulites usually start to partially melt(so we rename them migmatites to clarify) which looks really cool! But to be clear, metamorphic rocks never fully melt otherwise they would be considered igneous/get renamed. If you did this you could add in geodes/agate, petrified trees and the like, to the volcanic rocks and you could add labradorite/moonstone, garnets, quartz/smoky quartz, biotite, topaz, and aquamarine to the middle crust igneous rocks. Migmatites don't really add anything to the lowest layer, just vibes...
those squiggles look like granite right?! that's because it is! that is melted rock that re-solidified.
In terms of likelihood for occurrence, Other than what I listed for sedimentary rocks, and making diamonds a rarer drop rate for peridotites, I feel it is up to your own discretion.
Also, apologies I am not going to proofread this, which is honestly just my brand at this point, but if you need clarity please message me and thanks for reaching out to learn about geology! I can't express how happy it makes me when people put in an effort to have correct geology.