Meteorite Renchen, detailed view of fragment R3A showing a millimeter-sized merrillite–apatite aggregate and troilite. — Photo: Meteoriten-Deutschlands · CC BY-SA 4.0
Merrillite
An anhydrous sodium-calcium-magnesium phosphate — a signature mineral of meteorites and lunar rocks.
Intro adapted from Wikipedia (CC BY-SA).
Merrillite is an IMA-recognized mineral species in the phosphate class, with the chemical formula Ca₉NaMg(PO₄)₇.
It crystallizes in the hexagonal crystal system (space group R3c). It is a member of the Cerite structural group.
Key properties: specific gravity 3.1; refractive index 1.622; optically uniaxial.
IMA symbol Mer, IMA status: approved, named in 1917.
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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