I'm not equipped to quote primary sources, but Wikipedia gives us:
" The Ancient Greeks referred to quartz as κρύσταλλος (krustallos) derived from the Ancient Greek κρύος (kruos) meaning "icy cold", because some philosophers (including Theophrastus) understood the mineral to be a form of supercooled ice.
Roman naturalist Pliny the Elder believed quartz to be water ice, permanently frozen after great lengths of time. He supported this idea by saying that quartz is found near glaciers in the Alps, but not on volcanic mountains, and that large quartz crystals were fashioned into spheres to cool the hands. This idea persisted until at least the 17th century."
I must assume that this is all literally true in Mythic Europe.
But how can an enterprising magus best exploit this?
Using vulgar alchemy to design a new focus for ice.
Otherwise, just based on existing hermetic magic, not much more.
But it could be a good story seed. Could the larger cristals be eggs waiting to hatch ? Which creature ? Elemental or Spirit ? Mythic birds ? Dragons are known for nesting in the Alps. There are also frost giants.
Or Tatzelwurm - Wikipedia
I come from a town which is surrounded in quartz nodes, because it used to be a goldfield and gold is found in veins in quartz. There's got to be something you can do about the unfreezing ice and producing gold.
I have thrown Tazzelwürme in two sizes at my party in my saga: "Cat" and "Lion" sized. The players have found their nest with the huge draconic egg layer. I have one possible end boss for my saga.
I chose to have serpentinite as the Tatzelwürme's associated stone, since they are serpentine monsters...
Gold mining is certainly a possibility, and might be less traumatic to the local economy than many such schemes.
I haven't crunched the mechanics yet but it might be a good way to get non-ritualistic vis-free permanent creation by way of Perdo Ignem.
A smashy water elemental might be feasible.
Might be pushing things to allow a quartz vein or node to count as "a body of water", particularly for the purposes of Enchantment of the Scrying Pool, but that spell is already pulling some non-Hermetic weirdnesses, so it could be a direction for research.
From other examples we've seen, it's Items of Virtue that take on the weird Pliny origins. So, Quartz of Virtue would be found as long-frozen ice; go digging into Alpine glaciers if you need some.
Pliny also thinks that gems reproduce, so you can probably apply Herisson's breakthrough on Hermetic Stirpes to Quartz of Virtue. Garden some quartz Aquam vis in your glacier.
Yes... the Object of Virtue approach does appeal to my sensibilities.
Of course, that prompts the question as to what Minor Virtue it should bestow if Enriched. My first inclination is something like Lesser Immunity to Hot Weather.
I'm seeing a cave of Quartz that's used as a Scrying Room, like standing inside a Palantir. It feels like the sort of thing a Very Old Mostly Gone Tradition would get up to.
Megalith stones with Quartz containing gold veins are often found as pointer stones within various Circles and other structures all around North Western Europe. Additionally, a series of quartz quarries on Harris were used to construct shamanistic staffs. Assumed to be used in fire divination rituals. Sadly, we have lost all the myths in this area to time.