Montmorillonite in Quartz

specimen number:
2282107

location:
White Queen Mine, San Diego Co., California, USA

description:
A single terminated loose crystal of quartz, this included with white montmorillonite. in good condition.

The White Queen mine, located on Hiriart Mountain in the Pala district of San Diego County, California, is a pegmatite deposit mined for mineral specimens. Geologically, the locality consists of a granitic pegmatite dike hosted within Cretaceous-aged tonalite and gabbro belonging to the Peninsular Ranges Batholith. Internal zonation within the pegmatite developed pocket cavities containing quartz, spodumene, lepidolite, and cesium-bearing morganite beryl, with the primary minerals often embedded in clay. Mining activity at the site commenced around 1900 following the initial discovery of gemstone pockets on the mountain. The mine was worked intermittently by various independent operators during the early twentieth century, with the most sustained period of specimen production occurring under the ownership of Norman Dawson from 1947 through the 1980s.

Montmorillonite is a soft phyllosilicate clay mineral belonging to the smectite group. It forms through the hydrothermal alteration or weathering of aluminum silicate minerals, particularly in alkaline environments. In pegmatite deposits, it commonly occurs as a fine-grained mass that fills pocket cavities and encapsulates primary crystals.

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