Leucosphenite

BaNa4 Ti2 B2 Si10 O30°c 2001 Mineral Data Publishing, ver sion 1.2

Crystal Data: Monoclinic. Point Group: 2=m: Crystals tabular and elongated k [100],
typically wedge-shaped, to 3 cm; as rosettes and laminated masses. Twinning: Common? f001g, contact plane f001g.
Physical Properties:
Cleavage: f010g, f001g, distinct. Fracture: Uneven to subconchoidal.
Tenacity: Brittle. Hardness = 6{6.5 D(meas.) = 3.04{3.09 D(calc.) = 3.103
Optical Properties: Transparent to translucent. Color: Colorless, white, pale to dark green,pale yellow, pale gray to blue; brown to black and sectored from inclusions. Streak: White.
Luster: Vitreous to pearly.
Optical Class: Biaxial (+). Orientation: Z = b; Y ^ c ' 0 ± . Dispersion: r > v; may becrossed. ® = 1.644{1.648 ¯ = 1.660{1.664 ° = 1.687{1.691 2V(meas.) = 75 ± {78 ±Cell Data: Space Group: C2=m: a = 9.814(4)¯ = 93:35(3)± Z = 2

b = 16.851(5)c = 7.210(3)X-ray Powder Pattern: Mont Saint-Hilaire, Canada.
4.22 (100), 8.45 (90), 3.37 (70), 2.891 (60), 3.31 (50), 2.813 (40), 2.732 (40)
Chemistry:
SiO2
TiO2
ZrO2
B2 O 3Al2 O 3Fe2 O 3
Nb2 O5
FeO

(1)
54.3
13.92
0.00
6.36
0.00
0.28
0.1

(2)
53.66
14.52
0.00
6.6
0.11
0.77
0.04

MnO
MgO
CaO
SrO
BaO
Na 2O
K2 O
H2 O

(1)
trace
0.15
0.00
0.03
13.00
10.70
0.79
0.00

Total

99.63

(2)
0.00
0.00
0.06
11.98
11.61
0.51
99.86

(1) Inagli massif, Russia; corresponds to (Ba0: 94 Fe0:04 Mg 0:04 )§= 1:02 (Na 3:82 K0:18 )§= 4:00
Ti 1:92 B2:02 Si 10 O29:95 : (2) Mont Saint-Hilaire, Canada; by electron microprobe, corresponds to(Ba 0:94 Ca 0:01) §=0:95 (Na 4:10 K0:12 )§= 4:22 (Ti 1:99 Nb 0:06 ) §=2:05 B2:08 Si9:78 O29:90 :Occurrence: In pegmatite in syenite (Greenland, Russia, Canada); in aegirine-feldspar veins(Inagli massif, Russia); an authigenic mineral in shales (Utah and Wyoming, USA).
Association: Elpidite, aegirine, epididymite, albite, polylithionite (Narss^a rssuk, Greenland);arfvedsonite, eudialyte, neptunite, lamprophyllite, lorenzenite (Inagli massif, Russia); albite,aegirine, narsarsukite, molybdenite, calcite, °uorite (Mont Saint-Hilaire, Canada).
Distribution: From Narss^a rssuk, Greenland. In the USA, from the Green River Formation,in the Uinta basin, Utah and in the Bridger basin, Sweetwater Co., Wyoming. At MontSaint-Hilaire, Quebec, Canada. From the Inagli massif, 30 km west of Aldan, Yakutia, and in theLovozero massif, Kola Peninsula, Russia. From the Dara-i-Pioz massif, Alai Range, Tien Shan,Ta jikistan. At Ohmi, Niigata Prefecture, Japan.
Name:

From the Greek for white and wedge, its color and crystal habit.

Type Material: University of Copenhagen, Copenhagen, Denmark; The Natural History
Museum, London, England; Harvard University, Cambridge, Massachusetts; National Museum of
Natural History, Washington, D.C., USA, 135739, R3878.
References: (1) Dana, E.S. and W.E. Ford (1909) Dana's system of mineralogy, (6th edition),app. II, 64. (2) Ye¯mov, A.F. and Z.T. Kataeava (1959) The ¯rst discovery of leucosphenite inAll rights reserved. No par t of t his publication may b e reproduced, stored in a retrieval system or trans mitt ed inany form or by any means, electronic, mechanical, photocopying, recor di ng, or ot herwise without the prior written
permis sion of Mineral Data Publi shing.

the USSR. Doklady Acad. Nauk SSSR, 129, 896{899 (in Russian). (3) Chao, G.Y. and D.H.
Watkinson (1972) Leucosphenite from Mont St. Hilaire, Quebec. Can. Mineral., 11, 851{860.
(4) Pabst, A. and C. Milton (1972) Leucosphenite, and its occurrence in the Green River
Formation of Utah and Wyoming. Amer. Mineral., 57, 1801{1822. (5) Malinovskii, Y.A., N.A.
Yamnova, and N.V. Belov (1981) Re¯ned crystal structure of leucosphenite. Doklady Acad. NaukSSSR, 257, 1128{1132 (in Russian). (6) (1981) Chem. Abs., 95, 53078 (abs. ref. 5).

All rights reser ved. No part of this publicat ion may be reproduced, stored in a retrieval s yst em or transmitted inany form or by any means, elect ronic, mechanical, photocopying, recording, or otherwise without the prior wri ttenp ermiss ion of Mineral Dat a Publishing.