Quartz

specimen number:
2292373

location:
Sawtooth Mtns., Idaho, USA

description:
A large glassy translucent smoky quartz crystal. Neat locality example.

The Sawtooth batholith, located in central Idaho, is a major Eocene epizonal pluton that intruded into the older Cretaceous granites of the Idaho batholith approximately 47 million years ago. Geologically associated with the Challis volcanic-plutonic event, this pink, alkali-feldspar granite cooled rapidly at shallow crustal levels, creating numerous gas-rich cavities known as miarolitic pockets. Historically, these pockets have been sought after by mineral collectors for their distinct assemblages of minerals, including smoky quartz, microcline, fluorite, beryl, and topaz. The smoky quartz from this region developed its dark color over millions of years due to natural, low-level radiation from radioactive elements within the surrounding granite, which altered the quartz crystal lattice.

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