Quartz: The family name for crystals composed
of silica or
silicon
dioxide occurring in hexagonal crystals. The most common variety is
colorless and transparent. This is often referred to as Clear Quartz, Rock
Crystal or simply Quartz. The crystalline varieties include:
amethyst,
ametrine,
citrine,
rose quartz, and
smoky quartz. There are a variety of
crypto-crystalline varieties including agate
(chalcedony),
onyx,
sardonyx, carnelian,
sard,
chrysoprase, bloodstone,
jasper, and
prase. (see individual listings). Quartz is an essential constituent of
granite, forms the rocks
quartzite and , and makes most of the
sand of the seashore.
Quartzite: A hard rock made of interlocking
quartz crystals formed when
sandstone has been subjected to intense
heat and pressure.
Copyright 2007
