1. Chalcedony was once thought to be a fibrous variety of cryptocrystalline quartz. 2. Turquoise is nearly always cryptocrystalline and massive and assumes no definite external shape. 3. Novaculite is a form of microcrystalline or cryptocrystalline quartz. 4. Flint and chert are the most commonly knapped materials and are compact cryptocrystalline quartz. 5. These magnesites often are cryptocrystalline and contain silica in the form of opal or chert. 6. The apatite in phosphorite is present as cryptocrystalline masses referred to as " collophane ". 7. Cryptocrystalline rocks are good to use for ground stones because they have a very fine grain structure.8. The cryptocrystalline varieties are either translucent or mostly opaque, while the transparent varieties tend to be macrocrystalline. 9. This is a cryptocrystalline form of silica, consisting of fine intergrowths of the minerals quartz and moganite. 10. Blades are created using stones that have a cryptocrystalline structure and easily be fractured into a smooth piece without fracturing.
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