Rock&Gem Magazine|February 2021
Bob Jones
Editor’s Note: During the year-long celebration of Rock & Gem’s 50th Anniversary, we’ll be revisiting various articles from our archives and bringing them back for an encore publication. This article was initially published in the August 2001 issue of Rock & Gem and written by our esteemed Senior Consulting Editor Bob Jones.

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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