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Minasgeraisite, a new member of the gadolinite group from Minas Gerais, Brazil.

American Mineralogist

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Abstract

Minasgeraisite, Y2CaBe2Si2O10, a 9.833(2), b 7.562(1), c 4.702(1) A, beta 90.46(6)o, P21/a, Z = 2, is a new member of the gadolinite group. Found in quantities of only several hundred mg in the Jaguaracu pegmatite, Minas Gerais, Brazil, it occurs as 0.2 to 1.0 mm-diameter rosettes, coating and intergrown with milarite, albite, quartz and muscovite. The mineral is lavender to lilac purple and has a sheaf-like habit, with a grain size of <3-5 mu m. It is not magnetic and not fluorescent under either short-wave or long-wave ultraviolet radiations; H. approx 6-7, D(meas.) >4.25, D(calc.) 4.90 g/cm3, lustre is earthy to subvitreous and the streak is pale purple. Minasgeraisite is slowly soluble in common acids. The mineral has one excellent cleavage, (100) by analogy with gadolinite, and another good cleavage (001). Minasgeraisite is biaxial positive with alpha (colourless) 1.740(4), beta (pale greyish yellow) 1.754(4), gamma (lavender purple) 1.786(4), 2Vgamma 68o. Strongest powder XRD lines include 3.11(100), 2.830(100), 2.540(90), 1.768(35) A.-J.A.Z.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Minasgeraisite, a new member of the gadolinite group from Minas Gerais, Brazil.
Series title:
American Mineralogist
Volume
71
Issue:
3-4
Year Published:
1986
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
American Mineralogist
First page:
603
Last page:
607
Number of Pages:
5