8/16/2019 St Auro Lite
1/2
Staurolite (Fe2+ ; Mg)2 Al9 (Si; Al)4 O20 (O; OH)4°c 20 01
Mineral Data Publishing, v er sion 1 .2
Crystal Data: M onoclinic, pseudo-ort horhombic. Point Group:
2=m: Com monly in prismatic crys tals exhibiting f110g, f010g,
f001g, and f101g,typically rough, to 12 cm.Twinning: Commonly as
60± twins with f231g as twin plane, may be cyclic; less commonly as
90±crucifor m twins with f031g as twin plane.
Physical Properties: Cleavage: Distinct on f010g. Fr acture:
Subconchoidal.Tenacity: Brittle. Hardness = 7{7.5 D(meas.) =
3.74{3.83 D( calc.) =3.686
Optical Properties : Trans parent to opaque. Color: D ark reddis
h brown to blackish brown, yellowish brown, r arely blue; pale
golden yellow in t
hin section. St reak: White to grayish. Lus ter: Subvit reous t
o resinous.Opt ical Class: B iaxial ( +). Pleochroism: X = colorles
s; Y = pale yellow; Z = golden yellow.Orientation: X = b; Y = a; Z
= c. D ispers ion: r > v; weak. Absorption: Z > Y > X.® =
1.736{1.747 ¯ = 1.742{1.753 ° = 1.748{1.761 2V(meas .) = 80±
{90±
Cell Data: Space G roup: C 2=m: a = 7.863{7.871 b =
16.534{16.613c = 5.632{5.663
¯ = 90:00± ¡90:45± Z = 2
X-r ay Powder Pattern: Pizzo Forno, Switzerland. ( ICDD
15-397).3.012 (100) , 2.693 ( 100) , 2.372 ( 80), 3.559 (60), 2.400
(60), 1.515 (60),
1.511 (60)
Chemistry: (1) SiO227.82
TiO2 0.32Al2 O 3 54.91Fe2 O3 0.43Cr2 O 3 0.01FeO 12.39(1) MnO
0.22CoO 0.02
ZnO 0.19MgO 0.62Li2 O 0.36H2 O [2.26]Total [99.55]
(1) B lack Mountain, G raf ton Co., New Hampshir e, USA; by
electron and ion micr oprobe, average of 23 analyses, H O
determined on a s eparat e sample;corresponds to (Fe2+ Li Mg MnZn0:
02 )§ =1:81 ( Al8 :64 Fe3 +4 Ti0 :03 )§ =8:7 1 (Si3:8 5 Al0 :15 )§
=4:0 0 O24 H2: 08 :
Occurr ence: Common in pelit ic schists, gneis ses, and
argillaceous r ocks regionally metamorphosed to amphibolite grade;
also a detr ital mineral.
Association: Almandine, s illimanite, kyanite, tourmaline,
muscovite, quart z
8/16/2019 St Auro Lite
2/2
, chloritoid.
Di stribution: Wides pread, with ¯ne crystals from , for
example: at Pizzo Forno and Alpe Piona, Ticino, Switzerland. O n M
t. Greiner, Zillertal,Tirol, Austr ia. From the Keivy massif, Kola
Peninsula, Russ ia. Large twins, in the old Pr ovinces of Finis
tµere and M orbihan, in\B rittany," France. From Fanzer es, Por
tugal. In the USA, at Franconia, Gr aft on Co., New Hampshire;
Chest er ¯eld, Hamps hire Co., Mass achusett s; near Blue Ridge,
Fannin Co., Georgia; near Picures , Taos Co., New M exico. In
Brazil, in M inas Ger ais, fr om Rubellita and Ardenella; Agua
Quente, Rio Par do de Minas; and Fazenda Graniais .
Name: Derived from the G reek for a cros s, des cr ibing the
common twins.
References: (1) Dana, E.S. (1892) Dana's system of mineralogy,
(6th edition), 558{560. (2) Deer, W.A., R.A. Howie, and J. Zussman
(1982) Rock-forming miner als, (2nd edition) ,v. 1A, ort hosilicat
es, 816{866. (3) Hawthorne, F.C., L . Ungar et ti, R.
Oberti, F. Caucia, and A.Callegar i (1993) The crystal chemistry
of staur olite. I. Crys tal struct ure and s it e populat ions .
Can. Mineral., 31, 551{582. (4) Hawthorne, F.C., L. Ungaretti, R. O
bert i, F. Caucia, andA. Callegari (1993) II. Order-disorder and
the monoclinic ! orthorhombic phase transition. Can. M ineral., 31,
583{595. (5) Hawthor ne, F.C., L. Ungaret ti, R. Oberti, F. Caucia,
and A. Callegar i (1993) III. L ocal order andchemical composition.
Can. Miner al., 31, 597{616.All rights reserved. No par t o f t his
publica tion may b e reproduced, sto red in a retrieval sy stem or
trans mitt ed in any form or by a ny m eans, electronic, m
echanical, photo co py ing, recor di ng , or ot herw ise w ithout
the prior w ritten permis sion o f M ineral Da ta Publi shing .
