Of all the minerals found on Earth, quartz is the most common. It occurs in almost every type of rock. It comes in five common yet different crystallized forms and
many more noncrystalline forms. It is valuable in industry and communications. And it accepts other minerals, which give it colors and patterns that far exceed the beauty of any other mineral.
Quartz has long been the cornerstone of the gem and lapidary industry and the collecting hobby. We would be hard-pressed (even in 2020) to find many people who don’t have some variety of it in their collections.
This mineral has a relatively simple chemical structure. It is made of an atom of silicon (one of Earth’s most common elements) and two of oxygen (its most common element). Together, they form molecules that take the shape of a tetrahedron, rather like a pyramid with one corner pulled out to distort the whole. These, in turn, attach in a spiral fashion, forming beautiful hexagonal crystals that usually have pyramidal, or pointed, terminations.
If the quartz approaches pure silicon dioxide, it is clear and colorless, with air bubbles and miscellaneous impurities accounting for the milky hue often seen in quartz. If, however, other metal ions — iron or aluminum — become part of the internal arrangement, the potential for color is there.
When atoms combine to form molecules, they usually do so by sharing electrons, bonding them together. If everything balances electrically, the atom is stable and neutral. But when aluminum is present in quartz, it replaces some of the silicon atoms, and they differ in their electron balance. Silicon shares four of its electrons with two oxygen atoms in rock crystal.
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Digging at the McDonald Ranch
In June of 2020, the Central Oregon Rock Collectors club went on a field trip to the McDonald Ranch near Ashwood, Oregon. The McDonald Ranch offers petrified wood, angelwing agate, and thundereggs.
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Exploring the Science and Mindfulness Behind the Practice
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Mineral Constituents of the Chert Complex
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STUDYING THE PAST OF Petrified Wood
Trust Plant Anatomy To Be Your Guide When Working In the Present
THE GARNET FAMILY
Spanning the Spectrum of Mineralogy
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