Quartz with Albite

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A lustrous deep smoky quartz crystal 3.5 cm in size on a matrix of blocky albite crystals. This is in good condition. Jefferson County, Montana is a source of smoky quartz crystals, which are found within the pegmatites of the Boulder Batholith. Geologically, these crystals developed inside miarolitic cavities and pegmatite pockets hosted in the Cretaceous quartz monzonite of the batholith structure. Natural radiation from the surrounding granitic rock interacted with trace aluminum impurities within the quartz lattice to produce the smoky brown-to-black coloration. Small-scale surface digging, localized quarrying, and amateur field collecting in areas such as Homestake Pass and Little Pipestone Creek became active during the mid-twentieth century, particularly from the 1950s onward. The locality has never supported large-scale industrial mining for quartz, but seasonal surface excavation and independent specimen harvesting have remained active intermittently over subsequent decades to supply the collector market.