Quartz with Adularia (irradiated)

specimen number:
9892095

location:
Miller Mtn Mine, Garland Co., Arkansas, USA

description:
Jet black lustrous crystals of quartz measuring to 3.0 cm in size on matrix with lustrous bladed crystals of albite. An attractive combination piece, the quartz has been irradiated to create the dark black color.

The Miller Mountain Mine, located near Jessieville in Garland County, Arkansas, has operated for decades as a prominent source of high-quality quartz crystal specimens, functioning primarily as a commercial and public fee-digging site managed by the Coleman family. Geologically, the mine is situated within the core of the Ouachita Mountains, where epithermal silica-rich hydrothermal fluids filled fractures and vugs in heavily deformed Paleozoic sedimentary strata, such as the Crystal Mountain Sandstone, during the Ouachita orogeny roughly 280 to 240 million years ago.

Irradiating colorless quartz to produce dark smoky quartz involves exposing natural or synthetic rock crystal to high-energy radiation, such as gamma rays, X-rays, or electron beams. This radiation source knocks an electron away from a trace aluminum impurity that substitutes for silicon within the crystal lattice, forming a trapped-hole center known as an [AlO4]0 defect. This specific atomic-level structural defect alters how light is absorbed across the visible spectrum, imparting a deep smoky brown or black coloration to the quartz.

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