How Quartz became the new Eye of Newt
I feel like babbling, writeblr, so strap in for some Asylumverse witch lore.
So, once upon a time, travel was much harder than it is today. If you were lucky, everyone in your community had complementary skill sets, so you could ask Bessie for help with your herb enchantments and you could pay her back with some charged metals or whatever. If no one nearby did any fire work, youd just have to wait til a wandering traveler happened to come by with what you needed and hoped you could afford it--OR, you could brew a potion.
Not all potions were meant to be consumed internally, in fact, many weren't consumable at all. A large pot left out in the storm with jars in it was a potion for bottled lightning. A broom of certain herbs tied together and spun a certain way was a potion for wind magic. Some certainly were "brew this with that and drink or rub it here", but a potion was just the common vernacular for an affinity recipe, a way to harness a power not otherwise available to you.
Enter the modern era, and things from far away are easy to obtain--including people. Potions were still popular for a time (if nothing else because witch culture is loathe to depart from tradition) as new and more exotic ingredients could be more readily had. One of those ingredients was the crystal.
Suddenly, gems of various type, shape, and size were popping everywhere. Along with the new "witch shops" came the crystal craze. Especially quartzes. Easily programmable, available in a wide range of colors and sympathies, small and highly transportable, the crystal became the new catch all for power containment. You could leave a crystal out to catch lightning and not have to leave your cookpot out all night. You could condense your ingredient cabinet to a few trays of cleverly arranged (and aesthetically pleasing) gems. You could even *gasp* not keep a stockpile lying around, and just go buy things as needed.
The modern young witch uses crystals for everything. Potions have become the 1950's casseroles of the witching world. Young witches might use them out of nostalgia, or some weirdly ironic/hipster logic, but for the most part, potions are out, crystals are in.