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( Article orginally published November 1961 )
The six-sided crystals, with the long axis perpendicular to the axis of these sides, and having a hardness of 7, is quartz. Actually, it may be possible to find some six-sided crystals with approximately 7 in hardness but they will be rare.
And of course generally quartz crystals are clear-that is unless they are orange colored (citrene) or blueviolet (amethyst), or are coated with some other mineral (however thin a coating) such as manganese, etc.
Now if you are sufficiently mixed up, we can go on about quartz crystals. They may be cloudy to dead white, or so etched by ground acid that you cannot see into them at all. This will be rather general of quartz crystals found in fluorite mines. Hydrofluoric acid is the one acid that eats quartz.
The faces of quartz are generally striated at right angles to the short axes on the surface. This has to do with the crystal's growth and is one very good way to determine quartz from other crystals.
The top or termination is commonly very definite and approximately 40 degrees angle to the sides. However a rare occurrence in some areas shows that the angle curves from the plane of the side to that of the termination plane.
Quartz crystals have been found so minute that a microscope is necessary to see them and some from Brazil have been three feet in diameter and, though broken by earth movements, must have been 10 feet long.
It is from Brazil that the world gets most of its quartz for the many "crystal" items of the jewelry trade, but more important, Brazil supplies the world, including the Communist countries, with crystals for radar and other electronic instruments.
The crystal illustrated is the largest ever found in the state of Washington, where the writer is now hunting minerals. The crystal was discovered on the upper slope of White Horse Mountain in Snohomish county, Western Washington.
Other areas of the state where good quartz crystals are found, are near North Bend, west side of the Cascades, and Red Top Mountain on the east side.
This is not to discourage you from hunting crystals in other areas as they may turn up in any mining operation or quarry. We found some in a granite quarry along the side of the Great Northern Railroad just east of startup.
The Railroad was selling this granite to the city of Seattle for a fill along the waterfront. We went down there and found some nice crystals of both quartz and epidote in the rock in the fill.
The crystal pictured does not have a normal termination but is growing out of the parent crystal. This is called twinning and is common. If you look close you can see the extension of the tip portion inside the larger crystal. Study of these and all crystals is fascinating. Try it with a glass on your own. You may find it very rewarding.