"Key" - More accurately, Lock and Key. This is where a crystal has grown into or out of another and come loose from that hole. IMO? They work best together, because they can be used like a metaphysical padlock and key. Otherwise the usual “Keyed" (Lock. Aka the one with the keyhole or dent) can be locked and unlocked with woo/energy/power/sprowl.
"Lineated" crystals look like they have nested “clothes iron" markings on the faces. To me, energtically, these are absolutely a variety of Record Keeper. Scientifically, these are probably "Brazil Law Twin" quartz.
"Record Keeper" Crystals have raised triangles on their faces, and are supposedly used to “store" information. Lots of books waffle on about Atlantis, Lemuria and the moon-litten landscapes of Ye Olde Leng. I… don’t really believe them. But what I think is that disembodied things might be able to nudge the formation of a crystal, or maybe even decided to use it as their home. Poke around, see what comes out. It's often helpful, if not always clearly-understood. Don’t pay an ass-ton thinking you’re going to unlock the secrets of Atlantean Dolphin Mastery, though.
So, in my opinion? The best choice is Arkansas quartz. I’ve been to mines there (SPECIFICALLY Blue Moon Mine). Yes, they use boomsplode, but the land/land spirits really don’t seem to care, and the wildlife isn't really all that bothered (deer and birds scatter, then wander back). They’ve seen worse in the course of natural geology, and our little pop-pops don’t scare them. They use small to mid-sized equipment. The land/spirits don’t really care. They sort clean and sell - the land cares a little about the cleaning process (oxalic acid, used to clean crystals, is incredibly toxic and bad for the environment), but most places sell mine-run by the bushel for a reasonable price (uncleaned, still covered in red mud).
Digging your own (been there, done that) is incredibly rewarding and interesting. You’re literally in the dirt with them. Some mines will allow you to come with them while they open a fresh pocket and you get to pick it clean (the fee is… in line with that awesomeness). You also get a feel for particular crystals shouting “DUDE, ME! GRAB ME!" and finding an amazing specimen coated in mud and grime, smiling at you happily because it waited in that soil millions of years for your slow, evolving, self. Just the soil from these places is a treasure trove of microscopic crystals - I sat down with 600x magnification and some tweezers and located dozens of configurations (because I’m a nerd).
(from a slightly shorter post on my tumblr)