Black Mountain Quarry is located in the eastern member of a group of three pegmatites. The Pegmatite is an irregular intrusion in a quartz-mica shist and micaceous quartzite. The principal minerals in the deposit are cleavelandite, muscovite, quartz, spodumene, lepidolite, and tourmaline. Three zones are present in the pegmatite, as well as many replacement bodies. Schorl occurs in the border and intermediate zones, while elbaite is common in the replacement bodies. Small crytals of brown tourmaline, possibly dravite, have been reported from both the border zone and adjoining country rock. The tourmaline at Black Mountain Quarry is embedded in the pegmatite. Some of the elbaite is green or blue, but most of it is pink. In fact, pink tourmaline is unusually abundant in this location. It forms fan shaped crystal aggregates in lilac-colored lepidolite, a combination that results in very attractive specimens. The quarry has also produced crystals of eosphorite.

The Black Mountain Mineral Deposit was first discovered in 1878. The quarry changed hands several times during the turn of the century and it was worked intermittently for mica and feldspar. The only extended activity occurred from 1931 to 1942 whne it was mined for scrap mica, beryl, spodumene, lepidolite, and feldspar. The quarry has not been worked much since then.