Smythite

Fe3+x S4 (x = 0 to 0.3)
c 2001-2005 Mineral Data Publishing, version 1

Crystal Data:

Hexagonal. Point Group: 3 2/m.

As very thin hexagonal flakes, to 2 mm.

Physical Properties:
Cleavage: Perfect basal. Fracture: Subconchoidal. Tenacity: Flexible
and elastic lamellae. Hardness = n.d. VHN = 388 D(meas.) = ∼4.32 D(calc.) = ∼4.32
Strongly ferromagnetic, crystals attracted edge-on.
Optical Properties: Opaque. Color: Jet-black with a brown tinge against a whitebackground, pale bronze-yellow viewed on the mirrorlike base; in polished section, pinkish cream.
Streak: Dark gray. Luster: Metallic; splendent on basal section. Pleochroism: Strong; grayish
yellow to reddish brown. Anisotropism: Strong; yellow and blue-gray.
R1 –R2 : n.d.
Cell Data:

Space Group: R3m. a = 3.4651(5)c = 34.34(2)Z=3

X-ray Powder Pattern: Bloomington, Indiana, USA.
1.732 (100), 1.897 (80), 1.979 (70), 11.5 (60), 3.00 (60), 2.56 (60), 2.26 (60)Chemistry:FeNiCu

(1)
56.98
1.04

(2)
57.81
0.07
0.03

(3)
56.64

(1)CoS

40.92

(2)
0.03
41.33

(3)
43.36

Total 98.94
99.27
100.00(1) Bloomington, Indiana, USA; by electron microprobe, average of seven analyses; corresponds
to (Fe3.20 Ni0.06 )Σ=3.26 S4.00 . (2) Landsberg, Germany; by electron microprobe, corresponds toFe3.21 S4.00 . (3) Fe3 S4 .
Occurrence: Formed as a low-temperature oxidation product of the strongly magnetic
monoclinic phase of pyrrhotite, as inclusions in calcite crystals in quartz geodes; also inhydrothermal veins.
Association: Pyrite, greigite, mackinawite, pyrrhotite, marcasite, magnetite, sphalerite, galena,chalcopyrite, calcite.
Distribution: In the USA, in Monroe Co., Indiana, from a road cut about 3 km northof Bloomington [TL], and near Unionville; at the Kramer borate deposit, Boron, Kern Co.,
California; and from near Helena, Lewis and Clark Co., Montana. In Canada, from the Silverfields
mine, at Cobalt, and the Nicopor mine, north of Schreiber, Ontario; in the Bird River mines, Lac
du Bonnet area, Manitoba; and elsewhere. In Ukraine, from the Kimmerian sedimentary ironores of the Kerch Peninsula. In the Kamaishi mine, Iwate Prefecture, Japan. In the Lengenbachquarry, Binntal, Valais, and Trimbach, near Olten, Switzerland. In Germany, from Hartenstein,Saxony; in the Clara mine, near Oberwolfach, Black Forest; and at Landsberg, near Obermoschel,
Rhineland-Palatinate. From the Ceragiola quarry, near Seravezza, Tuscany, Italy. At Wadi Kamal,Saudi Arabia.
Name: Honors Professor Charles Henry Smyth, Jr. (1866–1937), economic geologist andpetrologist, Princeton University, Princeton, New Jersey, USA.
Type Material: Harvard University, Cambridge, Massachusetts, 106149; National Museum of
Natural History, Washington, D.C., USA, 112704.
References: (1) Erd, R.C. and H.T. Evans, Jr. (1956) The compound Fe3 S4 (smythite)found in nature. J. Amer. Chem. Soc., 78, 2017. (2) (1956) Amer. Mineral., 41, 815–816(abs. ref. 1). (3) Erd, R.C., H.T. Evans, Jr., and D.H. Richter (1957) Smythite, a new ironsulfide and associated pyrrhotite from Indiana. Amer. Mineral., 42, 309–333. (4) Taylor, L.A.
(1970) Smythite, Fe3+x S4 , and associated minerals from the Silverfields mine, Cobalt, Ontario.
Amer. Mineral., 55, 1650–1658. (5) Taylor, L.A. and K.L. Williams (1972) Smythite, (Fe, Ni)9 S11— a redefinition. Amer. Mineral., 57, 1571–1577. (6) Fleet, M.E. (1982) Synthetic smythite andmonoclinic Fe3 S4 . Phys. Chem. Minerals, 8, 241–246. (7) Krupp, R.E. (1994) Phase relations
and phase transformations between the low-temperature iron sulfides mackinawite, greigite, andsmythite. Eur. J. Mineral., 6, 265–278.
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.