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Afghanite (Na Ca K) (Si Al) O (SO CL CO) H O

Afghanite is a blue hexagonal mineral belonging to the cancrinite mineral group. It forms as stout to slender tabular laths and rounded grains. Afghanite is transparent with a vitreous luster and has a hardness of 5.5-6. It is uniaxial positive and was first discovered in Sar-e-Sang, Afghanistan occurring in thin veinlets cutting lazurite crystals. Afghanite's chemical composition involves sodium, calcium, potassium, silicon, aluminum, oxygen, sulfur, chlorine and carbonate.

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25 views1 page

Afghanite (Na Ca K) (Si Al) O (SO CL CO) H O

Afghanite is a blue hexagonal mineral belonging to the cancrinite mineral group. It forms as stout to slender tabular laths and rounded grains. Afghanite is transparent with a vitreous luster and has a hardness of 5.5-6. It is uniaxial positive and was first discovered in Sar-e-Sang, Afghanistan occurring in thin veinlets cutting lazurite crystals. Afghanite's chemical composition involves sodium, calcium, potassium, silicon, aluminum, oxygen, sulfur, chlorine and carbonate.

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ramzchile
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Afghanite (Na; Ca; K)8 (Si; Al)12 O24 (SO4 ; Cl; CO3 )3 ² H2 O

°
c 2001 Mineral Data Publishing, version 1.2

Crystal Data: Hexagonal. Point Group: 6=m 2=m 2=m; 6mm; or 6 m2: As stout to
slender, thin tabular laths and as rounded grains.
Physical Properties: Cleavage: Perfect on f1010g. Fracture: Conchoidal. Hardness = 5.5{6
D(meas.) = 2.55 D(calc.) = 2.65
Optical Properties: Transparent. Color: Blue; in thin section, colorless. Luster: Vitreous.
Optical Class: Uniaxial (+). ! = 1.523(2) ² = 1.529(2)
Cell Data: Space Group: P 63 =mmc; P 63 mc; or P 62c: a = 12.77(3) c = 21.35(4) Z=3
X-ray Powder Pattern: Sar-e-Sang, Afghanistan.
3.688 (100), 3.298 (100), 4.82 (80), 3.997 (60), 2.865 (60), 2.130 (60), 1.792 (60)
Chemistry: (1) (2)
SiO2 30.8 32.96
Al2 O3 25. 25.45
CaO 16.5 11.98
Na2 O 12.6 12.52
K2 O 2.7 3.07
Cl 4.6 3.98
H2 O 0.7
CO2 0.4
SO3 8.5 10.82
¡O = Cl2 1.0 0.9
Total 100.8 99.88

(1) Sar-e-Sang, Afghanistan; corresponds to (Na4:86 Ca3:52 K0:69 )§=9:07 (Si6:13 Al5:87 )§=12:00 O25:21
[Cl1:55 (SO4 )1:27 (CO3 )0:11 ]§=2:93 ² 0:46H2 O: (2) Edwards, New York, USA; by electron microprobe,
corresponds to (Na4:63 Ca2:45 K0:75 )§=7:83 (Si6:28 Al5:72 )§=12:00 O24:08 [(SO4 )1:55 Cl1:29 ]§=2:84 :
Mineral Group: Cancrinite group.
Occurrence: In thin veinlets cutting lazurite crystals (Sar-e-Sang, Afghanistan); in silici¯ed
limestone xenoliths in pumice (Pitigliano quarry, Italy).
Association: Lazurite, sodalite, nepheline, phlogopite, olivine, diopside, vesuvianite, calcite,
pyrite.
Distribution: At Sar-e-Sang, Badakhshan Province, Afghanistan. In Russia, in the Malaya
Bystraya and Tultuy lazurite deposits, near Lake Baikal, and in other unspeci¯ed deposits in
eastern Siberia. From Lyadzhuar-Darinsk, Pamir Mountains, Tajikistan. In Italy, at the Pitigliano
quarry, near Grosseto, Tuscany; on Monte Somma, Campania; from Vetralla and Bassano, Latium.
In the Edwards mine, Edwards, St. Lawrence Co., New York, USA. At Lake Harbour, Ba±n
Island, Newfoundland, Canada.
Name: For the country of ¯rst occurrence, AFGHANistan.
Type Material: Mineralogy-Crystallography Laboratory, University Pierre and Marie Curie,
Paris; National School of Mines, Paris, France; The Natural History Museum, London, England,
1969,72.
References: (1) Bariand, P., F. Cesbron, and R. Giraud (1968) Une nouvelle espµece min¶erale:
l'afghanite de Sar-e-Sang, Badakhshan, Afghanistan. Comparaison avec les min¶eraux du groupe
de la cancrinite. Bull. Soc. fr. Min¶eral., 91, 34{42 (in French with English abs.). (2) (1968)
Amer. Mineral., 53, 2105 (abs. ref. 1). (3) Hogarth, D. (1979) Afghanite: new occurrences and
chemical composition. Can. Mineral., 17, 47{52. (4) Parodi, G.C., P. Ballirano, and A. Maras
(1996) Afghanite from Mount Vesuvius: a rediscovery. Mineral. Record, 26, 109{114.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in
any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written
permission of Mineral Data Publishing.

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