Mineral Guide > Precious Stones > Crystalline Quartz gem stones

Crystalline Quartz gem stones

This is the most abundant, most durable, and most indestructible of common minerals. There is scarcely a sand beach, field, or mountain-side upon which this mineral cannot be found in some form or other. Its abundance is due not so much to its excess in quantity in the underlying rocks as to the fact that, being harder and less easily decomposed than other minerals, it remains after they are worn away.

Though so common, it appears in so great a variety of colors and different kinds of structure that a large collection of minerals looking very much alike might all be made up of Quartz. If they were all of quartz they would have the following characteristics: Hardness, 7 (cannot be scratched with a knife blade) ; specific gravity, two and a half times as heavy as water ; no cleavage ; fracture conchoidal (shell-like) ; infusible before the blowpipe; insoluble in common acids. The numerous varieties of quartz can be grouped into two classes, the pheno-crystalline (plainly crystalline) and the crypto-crystalline (obscurely crystalline).

This article deals only with the plainly crystalline varieties. These include, among other varieties, rock crystal, amethyst, rose quartz, smoky quartz, and sagenitic quartz. These varieties all occur in well-formed crystals, and all have a vitreous luster, i, e., luster like that of glass. The differences between them are almost exclusively differences of color.

Amethyst gem stone
Rock Crystal gem stone
Rose Quartz gem stone
Sagenitic Quartz gem stone
Smoky Quartz gem stone