Here I will collect all the quartz veins i've found so far. they are ubiquitous, at least in shale outcrops.
the Earth is constantly heaving and hawing and cracking, and hot fluids supersaturated with dissolved silica come seeping up under pressure to fill the cracks. Does the pressurized fluid help make the cracks?
Often we can see parts of oucrop that have slid past other parts when a crack forms between them. Often we can see a smooth surface along this crack with paralell striations on it, called slickensides. Often there are quartz veins against the slickenside. Does the quartz filling in the crack aid in the rock being able to slide? Does it cause the slide? Or does it come in AFTER the slide? I do not know.
Often the quartz vein will have nice crystals, if it wasn't entirely full of quartz and the crystals have room to grow. Supposedly you can find lots of cool minerals in these, but i have not found them yet.
1) Rt 209 just north of Ellenville NY.
Rt 2 (congress street) up the hill from Troy, NY past the first traffic light
