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IMA no. 1999-036 |
ERCITITE |
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Formula |
Na2(Mn3+,Fe3+)2(PO4)2(OH)2*4H2O |
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Crystal data |
mon |
P21/n |
irregular agregates (200 - 400 µm) of xx (20 - 200 µm) en lattes disposées en houppes and en gerbes |
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Relationship to other species |
structural related to bermanite |
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Optical properties |
brown dark, black |
vitreous |
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Physical properties |
H= 3-4 |
D(meas.)= |
D(calc.)= 2.75 |
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Cell parameters and optical class |
a= 5.362 |
b= 19.89 |
c= 5.362 |
Z= 4 |
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biaxial (+) |
a= 90° |
b= 108.97° |
g= 90° |
VÅ3= 540.8 |
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X-ray powder diffraction data |
9.900, 2.644, 3.273, 3.126, 4.92, 2.542, 2.376 |
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Association |
microcline, quartz, petalite, amblygonite, montebrasite, lithiophillite orange-brown, rhodochrosite, albite, pollucite, apatite green and blue, sphalerite, eucryptite, zircon, collinsite, fairfieldite, whitlockite, collinsite |
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Type locality |
Tanco pegmatite, Bernic Lake (N-W shore), Winnipeg, Manitoba, Canada |
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Etymology |
T.Scott Ercit (1957-),of Research Division, Canadian Museum of Nature, an eminent student of the mineralogy of granitic pegmatites |
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Bibliographical ref. |
Fransolet, A.-M. & al., The Tanco pegmatite at Bernic Lake, southeastern Manitoba. XV. Ercitite, Na2(Mn3+,Fe3+)2(PO4)2(OH)2*4H2O, a new phosphate mineral species, Can.Min. (2000), 38(4), 893-898 |
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Comments:
a) undoubtedly a product of alteration and oxidation of lithiophillite;
b) the ercitite structure is also similar to that of tsumcorite;
c) the occurrence of an Fe3+-dominant analogue of ercitite seems a distinct possibility