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.

Hardness

5.5

Mohs

Luster

Metallic

Streak

Black

Transparency

Opaque

mineralrare

Montroseite

Hardness: 5.5
Luster: Metallic
Streak: Black
Transparency: Opaque

Is this montroseite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch montroseite with a known reference. Montroseite sits at Mohs 5.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Montroseite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Montroseite typically shows a metallic luster.
4
Match the color range
Compare against the expected color range: black.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic crystals, acicular, radiating sprays.

Often confused with

Montroseite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Iron Ore

Mohs 5-6.5

How to tell apart: Streak differs — Montroseite leaves black, Iron Ore leaves reddish-brown to black; luster reads metallic on Montroseite and metallic to submetallic on Iron Ore.

Compare →

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: (V,Fe)O(OH)
Mohs hardness: 5.5
Density: 4.7-4.8 g/cm³
Colors: Black
Streak: Black
Luster: Metallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Prismatic Crystals, Acicular, Radiating Sprays
Cleavage: Good in One Direction
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Sedimentary Sandstone Deposits
Typical price: $20-150 for rare micro-mounts or small specimens

Where rockhounds find montroseite

Classic worldwide localities

Montrose County, Colorado, USA
Grand County, Utah, USA
Otish Mountains, Quebec, Canada

Field-hunting tip

Look in sedimentary sandstone deposits country — that is the host setting where montroseite typically forms. If you start seeing vanoxite, corvusite, pyrite in float, you are in the right ground. Field specimens usually show a prismatic crystals, acicular, radiating sprays habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify montroseite?+

Mohs hardness is 5.5. It typically shows a metallic luster. The streak is black. Common colors include black.

Where is montroseite found?+

Notable localities include Montrose County, Colorado, USA; Grand County, Utah, USA; Otish Mountains, Quebec, Canada.

How much is montroseite worth?+

Typical asking prices fall in the range of $20-150 for rare micro-mounts or small specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like montroseite?+

Montroseite is most often confused with Iron Ore. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with montroseite?+

Montroseite commonly co-occurs with Vanoxite, Corvusite, Pyrite, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does montroseite form in?+

Montroseite typically forms in sedimentary sandstone deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is montroseite used for?+

Montroseite is used in collector, scientific research.

Find montroseite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.