Herderite

phosphate

pegmatite

Formula: CaBe(PO4)F
Anhydrous phosphate containing halogen, forms a series with hydroxylherderite.
There is some doubt whether the true end-member herderite exists in nature, and many reported occurrences may be hydroxylherderite rather than herderite (Mindat).
Specific gravity: 3.02
Hardness: 5 to 5½
Streak: White
Colour: Colourless, pale yellow, greenish-white; colourless in transmitted light.
Environments:

Pegmatites

Most herderite-series minerals are the product of late-stage processes in granite pegmatites, and significant fluorine enrichment in the fluids appears to result in the domination of herderite over hydroxylherderite (AM 93.1545-1549). The most commonly associated minerals are quartz, albite, muscovite, and clay. Microcline, if present, is etched (AM 63.913-917).

At the type locality, the Sauberg Mine, Ehrenfriedersdorf, Erzgebirge District, Germany, herderite is found as a pegmatite mineral formed during late-stage hydrothermal deposition (Mindat).

Herderite has been found at the following localities: Yichung, Jiangxi, China (AM 93.1545-1549, Mindat), Greifenstein, Erzgebirge District, Germany (MinRec 35.4.351, Mindat), the Skayangi pegmatite, Mogok, Myanmar (AM 93.1545-1549, Mindat), and Chhappu, Baltistan, Pakistan (MinRec 35.2.150, Mindat). It has also been found at several localities in Maine, USA, namely Stoneham, Hebron and Greenwood in Oxford county, and Mount Apatite and Berry's quarry in Androskoggin county (USGS bulletin 445).

Common impurities: H,OH

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