Quartz: The family name for naturally occurring crystals composed of silica or silicon dioxide occurring in hexagonal habit. 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. Quartz is an essential constituent of granite, forms the rock quartzite and forms most of the sand on the seashore.
Quatra-Foil: A design element with four divisions, as in a four-leaf clover