(Ca; Na; K)(Mg; Fe; Al)9 (Si; Al)8 O20 (OH)10 ² nH2 O

Corrensitec 2001 Mineral Data Publishing, version 1.2°

Crystal Data:n.d. Point Group: n.d.

As aggregates of clay-sized particles.

Physical Properties:
Cleavage: Perfect basal. Tenacity: Unctuous. Hardness = n.d.
D(meas.) = n.d. D(calc.) = n.d.
Optical Properties: Semitransparent. Color: Yellowish green. Luster: Dull, earthy.
Optical Class: Biaxial ({). Pleochroism: X = yellowish ocher; Y = Z = brownish green.
® = 1.560{1.585 ¯ = n.d. ° = 1.582{1.612 2V(meas.) = Small.
Cell Data:

Space Group: n.d.

Z = n.d.

X-ray Powder Pattern: Wellington Formation, Lyon Co., Kansas, USA; a 30 ºA d-spacingchanges to: air dried, 28{29; ethylene glycol, 32{33; on heating to »500 ± C, 23{29.
14.5 (100), 1.54 (90), 2.57 (80), 7.26 (70), 4.60 (60), 3.61 (50), 2.44 (50)
Chemistry:
SiO2
TiO2
Al2 O3Fe2 O3
MnO

(1)
37.2
0.4
15.5
6.7
0.01

(2)
34.
13.
7.

MgO
CaO
Na2 O
K2 O
H2 O(1)18.91.0
0.2
1.4
18.4

(2)
24.

Total

99.7[100.]

22.

(1) Sparta, Tennessee, USA; total Fe as Fe2 O3 ; traces of Zr, V, and Cu determined
spectrographically. (2) Do.; recalculated to 100% after removal of impurities.
Polymorphism & Series: A 1:1 mixed-layer interstrati¯cation of trioctahedral chlorite witheither a trioctahedral vermiculite or a trioctahedral smectite.
Occurrence: From diverse sedimentary environments, which produced clastic, carbonate,volcanoclastic, or evaporite rocks. Also a hydrothermal alteration product, may be formed underretrograde diagenetic conditions; in soils.
Association:Illite, chlorite, laumontite, gypsum, anhydrite, quartz, dolomite.

Distribution: Probably fairly widely distributed; a few localities with material known to meetthe de¯nition are: from Zaiserweiher, three km from Maulbronn, Baden-WÄurttemberg, and at
the HÄ
unstollen, near Holserode, Lower Saxony, Germany. At Wilkesley, near Audlem, Cheshire,and elsewhere in England. From Hillhouse quarry, Ayrshire, Scotland. In the USA, from Juniper
Canyon, Mo®at Co., Colorado; in the Wellington Formation, in Lyon Co., Kansas; in the Countyrock quarry, Sparta, White Co., Tennessee; and from a number of localities in west-centralMontana, as between Bowman's Corner and Wolf Creek, Lewis and Clark Co. From Packwood,Western Australia. From the Yamanaka area, Shimane Prefecture, and in the Yoshino mine,
Yamagata Prefecture, Japan.
Name: For Professor Carl Wilhelm Correns (1893{1980), Director of the Sedimentary
Petrography Institute, GÄottingen University, GÄottingen, Germany.
Type Material:

National Museum of Natural History, Washington, D.C., USA, 107373, 162265.

ÄReferences: (1) Lippmann, F. (1954) Ubereinen Keuperton von Zaisersweiher bei Maulbronn.
Heidelberg. Beitr. Mineral. Petrog., 4, 130{134 (in German). (2) (1955) Amer. Mineral., 40,
137 (abs. ref. 1). (3) Peterson, M.N.A. (1961) Expandable chloritic clay minerals from Upper
Mississippian carbonate rocks of the Cumberland Plateau in Tennessee. Amer. Mineral., 46,1245{1269. (4) Kopp, O.C. and S.M. Fallis (1974) Corrensite in the Wellington Formation,Lyons, Kansas. Amer. Mineral., 59, 623{624. (5) Yoshimura, T. and S. Okubo (1988) Refractive
indices and birefringence of corrensite and the related minerals. Mineral. J. (Japan), 14, 145{149.
(6) Reynolds, R.C., Jr. (1988) Mixed layer chlorite minerals. In: S.W. Bailey, Ed., Hydrous
phyllosilicates. Rev. Mineral. 19, MSA, 601{629. (7) Shau, Y.-H., D.R. Peacor, and E.J. Essene(1990) Corrensite and mixed-layer chlorite/corrensite in metabasalt from northern Taiwan:
TEM/AEM, EMPA, XRD, and optical studies. Contr. Mineral. Petrol., 105, 123{142.
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.