Smoky Quartz with Microcline (#75)

A single lustrous opaque to translucent cathedral growth dark smoky quartz with minor opaque dull tan microcline crystals and sections to ¾" maximum dimension.
North America Sawtooth Batholith, Idaho 3 ½" x 1 ½" x 1½"

 

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Specimen #9 is also smoky quartz, and the cause of the smoky color is discussed in the Learn More for that specimen. Microcline is variety of alkali feldspar, one of the most common minerals in the crust of the earth. Amazonite (specimen #42) is a blue green variety of microcline that contains trace amounts of lead (Pb).

The label says this is cathedral growth. Nope, that's not the same as the Crystal Cathedral, which is a church building in California. Cathedral growth is the parallel growth of shorter crystals parallel and close to a central longer crystal:

In cathedral growth, all of the corresponding faces are strictly parallel, so that all of them reflect light essentially simultaneously.