| An important rock-forming mineral that occurs in a wide variety of rocks (Granite, sandstone, quartzite). Macrocrystalline quartz specimens are semiprecious stones such as amethyst (purple), citrine (yellow), rose quartz, smoky quartz, or rock crystal (clear). Cryptocrystalline quartz (much smaller crystal size) types include agate, jasper, carnelian, and flint. Property values are typical of naturally occurring Quartz. Actual property values will vary from sample to sample. |
| SiO2, Silica, Silicon Dioxide |
