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Sardonyx
Onyx is a typically black-and-white banded variety of agate, a silicate mineral. The bands can also be monochromatic with alternating light and dark bands. Sardonyx is a variety with red to brown bands alternated with black or white bands. The name "onyx" is also frequently used for level-banded (parallel-banded) agates, but in proper usage it refers to color pattern not band structure.
Intro adapted from Wikipedia (CC BY-SA).
Sardonyx is a mineral variety of Quartz, with the chemical formula SiO₂.
It crystallizes in the trigonal crystal system.
Key properties: Mohs hardness 7; typically red or brown or white.
Collections: Gemstones.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data and a Wikipedia introduction — a full written entry hasn’t been published yet.
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