Discussion: What Mineral is Rarity's Cutie Mark?

So I just realized I have a bunch of semi-useless mineral knowledge at my disposal. You know what that means? Open-ended-overanalysis time! Take a look after the break and add your two-cents!



If Rarity's cutie mark is of a carved mineral or crystal then there is a long list of minerals that the cutie mark could represent, so assuming it's in its natural state to shorten the list of possibilities, we are left with:

Lazurite, which could potentially look like a geometric diamond when viewed from certain angles

Afghanite, which can on rare occasions be sort of diamond-shaped.

Azurite, which is typically prismatic but on rare occasions can look diamond-ish. Maybe a tad too bright-blue though.

Lots of people say Rarity's cutie mark looks like sapphires. I guess I could see that, but it's not all that exotic though.

Tanzanite seems popular these days, and is often angular, but would have to be doubly-terminated to look diamond-shaped.

Now for my favorites: from a geometrical standpoint anatase always resembles Rarity's cutie mark very closely, with a good diamond shape, and can be the right shade of light blue (this pic is of a somewhat darker one)

And my personal head canon: Rarity's Cutie Mark is of cumengite crystals:

For some specimens of Cumengite, the geometric similarities to Rarity's cutie mark are striking, though I'll admit cumengite is a few shades of blue too dark.

Also sure, Rarity's Cutie Mark could be actual diamonds, which can sometimes be blue, but in nature diamonds are typically a little rounded: not always an exact diamond shape. And even when they are they aren't stretched out along one axis like Rarity's cutie mark

I also imagine it is possible Rarity's Cutie Mark could represent an oddly-twinned Benitoite specimen, but that mineral is typically triangular and rarely twinned.

So... What do you commenters think? can you think of any other blue minerals/crystals that might fit the bill? Of the ones here, which do you think is most likely to be Rarity's cutie mark?


Hard mode: What species of butterfly might Fluttershy's cutie mark be? I found this, which might be helpful... But I'm sure there are more useful dichotomy keys and identification tools available out there. Perhaps they'd be easier to find with google scholar? Good luck, this is a tough one.