The mineral forms cryptocrystalline, often porous, masses, usually of white colour. Geologists use chert as a generic name for any type of microcrystalline or cryptocrystalline quartz. Chalcedony was once thought to be a fibrous variety of cryptocrystalline quartz. Enhydro agates are made up of banded microcrystalline or cryptocrystalline quartz. Most of the evidence uncovered was made of cryptocrystalline quartz. It is an agate, a cryptocrystalline form of quartz. Silica occurs in 3 forms&colon; crystalline, microcrystalline (or cryptocrystalline) and amorphous (non-crystalline). Other members of the cryptocrystalline silica family include agate, carnelian, and onyx. Turquoise is nearly always cryptocrystalline and massive and assumes no definite external shape. Agates such as the fairburn agate are also composed of cryptocrystalline silica. These cryptocrystalline rocks are composed of microscopic crystal like patterns. Flint and chert are the most commonly knapped materials and are compact cryptocrystalline quartz. Cryptocrystalline rocks fill the Pleistocene gravel beds on the Carmel platforms. Obsidian and cryptocrystalline silicates appear to be the most promising materials for destructive analysis. About 98% of waste flakes recovered are made of cryptocrystalline quartz (chert).