Montroseite is a rare vanadium oxyhydroxide mineral typically found as small, black, acicular, or prismatic crystals in vanadium-bearing sandstone deposits. It is often identified by its metallic luster and dark black streak, and it frequently alters to other vanadium minerals like vanoxite or corvusite when exposed to weathering.
Is this montroseite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch montroseite with a known reference. Montroseite sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic.
- 4Match the color rangeCompare against the expected color range: black, grayish black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: bladed, microscopic crystals.
Often confused with
Montroseite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Montroseite leaves black, Goethite leaves brownish yellow, yellow-orange, ocher-yellow; luster reads submetallic on Montroseite and imperfect adamantine metallic to dull earthy; silky when fibrous on Goethite.
How to tell apart: Streak differs, so Montroseite leaves black, Hematite leaves cherry-red or reddish brown; luster reads submetallic on Montroseite and metallic or submetallic to dull on Hematite.
Often found alongside montroseite
Minerals reported to co-occur with montroseite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- VO(OH)
- Mohs hardness
- 5.5-6.5
- Density
- 4.0 g/cm³
- Colors
- Streak
- Black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Bladed, microscopic crystals
- Cleavage
- {010} and {110}, good
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In relatively unoxidized Colorado Plateau-type U–V ores in sandstones; thought to be a primary mineral (Colorado, Utah, and Arizona, USA); in vanadiferous anthraxolite bitumen (Guangxi, China)
Where rockhounds find montroseite
Classic worldwide localities
- Bitter Creek, Jo Dandy, Whitney, and Virgin mines, Uravan district, Montrose Co., and the Matchless mine, Gateway district, Mesa Co., Colorado, USA
- Juniper mine, near Thompson, Grand Co., the Rex No. 2 mine, Temple Mountain, and Mi Vida mine, Monticello district, Emery Co., Utah, USA
- Martin, Mesa 4-1/2, and Cove mines, Carrizo Mountains, and the Monument No. 2 mine, Monument Valley, Apache Co., Arizona, USA
- Grants district, McKinley Co., New Mexico, USA
- Příbram, and in the Novoveska Huta deposit, Czech Republic
- Urcal deposit, La Rioja, and in the Huemul mine, Malargüe district, Mendoza Province, Argentina
Field-hunting tip
Where it forms: In relatively unoxidized Colorado Plateau-type U–V ores in sandstones; thought to be a primary mineral (Colorado, Utah, and Arizona, USA); in vanadiferous anthraxolite bitumen (Guangxi, China). If you start seeing paramontroseite, uraninite, corvusite in float, you are in the right ground. Typical habit: bladed, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify montroseite?+
Where is montroseite found?+
Is montroseite safe to handle?+
What rocks look like montroseite?+
What minerals are found with montroseite?+
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Find montroseite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
