Pinctada margaritifera - Two views of same specimen — Photo: Didier Descouens · CC BY-SA 4.0
Pearl
Also known as: June birthstone.
Concentric aragonite layers secreted by a mollusk — an organic gem rather than a true mineral, prized since antiquity.
Intro adapted from Wikipedia (CC BY-SA).
Pearl is a mineraloid, with the chemical formula Aragonite + conchiolin.
It crystallizes in the orthorhombic crystal system.
Key properties: Mohs hardness 2.5–4.5; typically white or pink or black or gray.
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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