Agate — Photo: Wikimedia Commons · CC BY 4.0
Chalcedony
Also known as: Blue chalcedony, Chrome chalcedony.
The family name for microcrystalline quartz — masses of silica crystals too small to see without magnification; includes agate, jasper and carnelian.
Intro adapted from Wikipedia (CC BY-SA).
Chalcedony is a mineral variety of Quartz, with the chemical formula SiO₂.
It crystallizes in the trigonal crystal system.
Key properties: Mohs hardness 6.5–7; typically white or gray or blue or brown or pink.
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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