Onyx Quartz
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Quartz is silicon dioxide, SiO2. Quartz is abundant in the Earth's crust, being the chemically simplest form of the silicates. All the samples here are displayed in the Smithsonian Museum of Natural History. One of the distinctive varieties of quartz is called onyx. The samples at right have a maximum dimension of about 3.5 cm and are from Brazil. |  |
Sardonyx Quartz
 | These are examples of sardonyx quartz from Brazil. The largest is about 2x2.5 cm. |
This sample is also from Brazil. Its dimensions are about 3x2.5 cm. |  |
Bloodstone Quartz
 | These example of bloodstone is from India and measures about 3x3 cm. |
Chrysoprase Quartz
This sample is from Marlborough mine, Queensland, Australia. Its dimensions are about 11x13 cm. |  |
Flint Quartz
 | This example of flint is from Gravesend, England and measures about 4x4 cm. |
| Minerals |
| HyperPhysics***** Geophysics | R Nave |