(V3+, Fe2+ , V4+ )O(OH)

Montroseite

c 2001-2005 Mineral Data Publishing, version 1

Crystal Data: Orthorhombic. Point Group: 2/m 2/m 2/m. As microscopic bladed crystals,
to 0.5 mm, flattened on {010}, with {110}, and terminated by {0.10.1}(?) and {121}; in veryfine-grained aggregates.
Physical Properties: Cleavage: {010} and {110}, good. Tenacity: Brittle. Hardness = Soft.
D(meas.) = 4.0 D(calc.) = 4.11 Rapidly transforms topotactically to paramontroseite in air.
Optical Properties: Opaque. Color: Black to grayish black. Streak: Black.
Luster: Submetallic.
Optical Class: Biaxial.
R1 –R2 : (400) 16.6–18.7, (420) 15.8–18.0, (440) 15.0–17.3, (460) 14.6–17.0, (480) 14.4–16.8, (500)
14.3–16.6, (520) 14.4–16.7, (540) 14.6–16.8, (560) 14.9–16.9, (580) 15.1–17.1, (600) 15.5–17.4, (620)
15.8–17.8, (640) 16.2–18.2, (660) 16.6–18.7, (680) 17.0–19.2, (700) 17.5–19.8
Cell Data:

Space Group: P bnm. a = 4.54

b = 9.97

c = 3.03

Z=4

X-ray Powder Pattern: Unspecified locality, USA.
4.31 (s), 2.644 (s), 3.38 (m), 2.495 (m), 2.217 (m), 1.512 (m), 2.423 (w)Chemistry:
V2 O4
V2 O3
SiO2Al2 O3FeO
H2 O

(1)
72.5
10.5

8.8
5.0

(2)
66.90
11.10
6.12
3.00
8.26
4.82

(3)
89.27

10.73

Total
[96.8]
100.20100.00(1) Bitter Creek mine, Colorado, USA; partial analysis. (2) Matchless mine, Colorado, USA.
(3) VO(OH).
Occurrence: In relatively unoxidized Colorado Plateau-type U–V ores in sandstones; thought tobe a primary mineral (Colorado, Utah, and Arizona, USA); in vanadiferous anthraxolite bitumen(Guangxi, China).
Association: Paramontroseite, uraninite, corvusite, hewettite, melanovanadite, pascoite,hummerite, pyrite, galena, barite, quartz.
Distribution: In the USA, at the Bitter Creek, Jo Dandy, Whitney, and Virgin mines, Uravan
district, Montrose Co., and the Matchless mine, Gateway district, Mesa Co., Colorado; in theJuniper mine, near Thompson, Grand Co., the Rex No. 2 mine, Temple Mountain, and Mi Vida
mine, Monticello district, Emery Co., Utah. In the Martin, Mesa 4-1/2, and Cove mines, Carrizo
Mountains, and the Monument No. 2 mine, Monument Valley, Apache Co., Arizona; in the Grants
district, McKinley Co., New Mexico; and in the Runge mine, Edgemont, Fall River Co., SouthDakota. At Přı́bram, and in the Novoveska Huta deposit, Czech Republic. In the Urcal deposit,
La Rioja, and in the Huemul mine, Malargüe district, Mendoza Province, Argentina. From theMounana uranium mine, Franceville, Gabon. In the Shanglin and Hechi bitumens, Guangxi,Zhuang Autonomous Region, China.
Name:For Montrose Co., Colorado, USA, where it was first found.

Type Material:National Museum of Natural History, Washington, D.C., USA, 106897, 106898.

References: (1) Weeks, A.D., E.A. Cisney, and A.N. Sherwood (1953) Montroseite, a newvanadium oxide from the Colorado Plateaus. Amer. Mineral., 38, 1235–1241. (2) Evans, H.T., Jr.
and S. Block (1953) The crystal structure of montroseite, a new vanadium member of the diasporegroup. Amer. Mineral., 38, 1242–1250. (3) Weeks, A.D. and M.E. Thompson (1954) Identificationand occurrence of uranium and vanadium minerals from the Colorado Plateaus. U.S. Geol. Sur.
Bull. 1009-B, 52–53. (4) Evans, H.T., Jr. and M.E. Mrose (1955) A crystal chemical study ofmontroseite and paramontroseite. Amer. Mineral., 40, 861–875.
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