Mineral Guide > Precious Stones > Beryl gem stone

Beryl gem stone

This mineral species includes a number of varieties which are highly valued as gems. These are, besides Beryl itself, the gems emerald, aquamarine, and golden beryl. Chrysoberyl, it may be noted, is not a variety of beryl, but a distinct species.

While these gems all differ in color, they are the same mineral and are practically identical in composition, hardness, and other properties. In composition they are a silicate of aluminum and glucinum, the percentage being, for normal beryl, 67 per cent. of silica, 19 per cent. of alumina, and 14 per cent. of glucina.

The beautiful green color of the emerald is probably due to a small quantity of chromium which it usually contains, though some authorities believe organic matter to be the coloring ingredient. To what substance the other varieties of the species owe their color is not known.

In hardness the varieties of beryl differ little from quartz, the hardness being 7.5 to 8 in the scale of which quartz is 7. They are somewhat inferior, therefore, to such gems as topaz, sapphire, and ruby in wearing qualities, although hard enough for ordinary purposes.

The specific gravity of beryl is also about like that of quartz, ranging from 2.63 to 2.80, the specific gravity of quartz being 2.65. The varieties of beryl are, therefore, relatively light as compared with other gems.

Beryl crystallizes in the hexagonal system. It usually occurs as six-sided prisms, commonly terminated by a single flat plane, but sometimes by numerous small planes, giving a rounded effect.

Occasionally it terminates in pyramidal planes which cause the prism to taper to a sharp point. The crystals sometimes grow to enormous size, exceeding those of any other known mineral. Ordinary beryl is a mineral of comparatively occurrence, being often found in granitic and rocks.

Aquamarine Beryl picture
Blue Beryl picture
Emerald Beryl in Matrix picture
Golden Beryl picture