(Mn2+ , Fe2+ , Mg)(Al, Fe3+)2 O4

Galaxitec 2001-2005 Mineral Data Publishing, version 1

Crystal Data: Cubic. Point Group: 4/m32/m. As octahedra and rounded grains, to 0.5 mm;
as exsolution blebs. Twinning: On {111} as both twin and composition plane, the spinel law,probable.
Physical Properties:
D(calc.) = [4.22]

Fracture: Conchoidal. Hardness = 7.5

D(meas.) = 4.234

Optical Properties: Opaque; may be translucent in thin section. Color: Black, red-brown, red
to yellow; in transmitted light, golden yellow, brownish orange, mahogany-red, deep red to reddish
black. Streak: Red-brown. Luster: Vitreous.
Optical Class: Isotropic. n = 1.923
Cell Data:

Space Group: F d3m. a = 8.258

Z=8X-ray Powder Pattern: Synthetic MnAl2 O4 .
2.492 (100), 2.921 (60), 1.4600 (45), 1.5896 (40), 0.8429 (30), 2.065 (25), 1.0749 (25)
Chemistry:
SiO2
TiO2
Al2 O3Fe2 O3
V2 O3
FeO

(1)
0.96
trace
45.71

16.36

(2)
< 0.05
56.3
4.6
0.14
0.0

(3)
0.30
0.13
48.0
8.9

MnO
CoOZnO
MgO
CaOTotal

(1)
34.03
trace
1.50
trace
98.56

(2)
39.1
0.25
0.43
0.83

(3)
39.9

101.7

99.0

1.79

(1) Bald Knob, North Carolina, USA; total Fe as FeO. (2) Do.; by electron microprobe,
Fe2+ :Fe3+ calculated from stoichiometry; corresponds to (Mn2+0.95 Mg0.04 Zn0.01 )Σ=1.00(Al1.90 Fe3+)O.
(3)Bonneval-sur-Arc,France;
byelectronmicroprobe, total Fe as Fe2 O3 ;0.10 Σ=2.00 4
3+3+
corresponds to (Mn2+Mg)(AlFeMnSi)
0.92
0.20
0.09 0.01 Σ=2.00 O4 .
0.08 Σ=1.00
1.70
Mineral Group:
Occurrence:deposits.

Spinel group.

In carbonate-rich, silica-undersaturated parts of metamorphosed manganese

Association: Alleghanyite, rhodonite, sonolite, spessartine, tephroite, kutnohorite,manganhumite, jacobsite, kellyite, alabandite (Bald Knob, North Carolina, USA); katoptrite,magnetite, manganostibite, magnussonite, tephroite, manganhumite, manganosite (Brattfors mine,Sweden).
Distribution: Occurs near Bald Knob, Alleghany Co., North Carolina, USA. In the Brattfors
and Jakobsberg mines, Värmland, Sweden. In France, found near Bonneval-sur-Arc, Haute-Savoie.
In Japan, found at the Noda-Tamagawa mine and Hijikuzu, Iwate Prefecture; the Oashi mine,Tochigi Prefecture; the Taguchi mine, Aichi Prefecture; the Ioi mine, Shiga Prefecture; and theFukumaki mine, Yamaguchi Prefecture.
Name: For Galax, Virginia, USA, close to Bald Knob, North Carolina, and for the plant, galax,
after which the town is named.
Type Material:n.d.

References: (1) Palache, C., H. Berman, and C. Frondel (1944) Dana’s system of mineralogy,(7th edition), v. I, 689–697. (2) Ross, C.S. and P.F. Kerr (1932) The manganese minerals of a veinnear Bald Knob, North Carolina. Amer. Mineral., 17, 1–18. (3) Chopin, C. (1978) Les paragèneses
réduites ou oxydées de concentrations manganésifères des “schistes lustrés” de Haute-Maurienne(Alpes françaises). Bull. Minéral., 101, 514–531 (in French with English abs.). (4) Essene, E.J.
and D.R. Peacor (1983) Crystal chemistry and petrology of coexisting galaxite and jacobsite andother spinel solutions and solvi. Amer. Mineral., 68, 449–455. (5) (1960) NBS Circ 539, 9, 35.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted inany form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written
permission of Mineral Data Publishing.