Roscoelite is a vanadium-rich mica that is easily identified by its distinctive olive-green to dark green color and micaceous, scaly habit. It is commonly found associated with gold deposits or vanadium-bearing sandstone and is often noted by collectors for its unusual chemistry and attractive green color.

Hardness

2.5-3

Mohs

Luster

Pearly

Streak

Light Green

Transparency

Translucent

mineraluncommonMica Group family

Roscoelite

Hardness: 2.5-3
Luster: Pearly
Streak: Light Green
Transparency: Translucent

Is this roscoelite?

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 roscoelite with a known reference. Roscoelite sits at Mohs 2.5-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Roscoelite leaves a light green streak.
3
Read the luster
Hold the specimen under a strong light. Roscoelite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: green, dark green, brownish green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: micaceous, scaly, massive, botryoidal.

Often confused with

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

mineral

Fuchsite

Mohs 2.5-3

How to tell apart: Streak differs — Roscoelite leaves light green, Fuchsite leaves white.

How to tell apart: Streak differs — Roscoelite leaves light green, Muscovite leaves white.

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Often found alongside roscoelite

Minerals reported to co-occur with roscoelite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: K(V,Al,Mg)₂(AlSi₃)O₁₀(OH)₂
Mohs hardness: 2.5-3
Density: 2.9-3.0 g/cm³
Colors: Green Dark Green Brownish Green
Streak: Light Green
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Micaceous, Scaly, Massive, Botryoidal
Cleavage: Perfect Basal
Rarity: Uncommon
Uses: Collector, Research
Host rock: Hydrothermal Veins, Sandstone
Typical price: $10-60 for small specimens

Where rockhounds find roscoelite

Classic worldwide localities

Placerville, California, USA
Colorado Plateau, USA
Mukka, South Australia
Siberia, Russia

Field-hunting tip

Look in hydrothermal veins, sandstone country — that is the host setting where roscoelite typically forms. If you start seeing quartz, pyrite, carnotite in float, you are in the right ground. Field specimens usually show a micaceous, scaly, massive, botryoidal habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify roscoelite?+

Mohs hardness is 2.5-3. It typically shows a pearly luster. The streak is light green. Common colors include green, dark green, brownish green.

Where is roscoelite found?+

Notable localities include Placerville, California, USA; Colorado Plateau, USA; Mukka, South Australia; Siberia, Russia.

How much is roscoelite worth?+

Typical asking prices fall in the range of $10-60 for small specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like roscoelite?+

Roscoelite is most often confused with Fuchsite, Muscovite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with roscoelite?+

Roscoelite commonly co-occurs with Quartz, Pyrite, Carnotite, Barite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does roscoelite form in?+

Roscoelite typically forms in hydrothermal veins, sandstone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is roscoelite used for?+

Roscoelite is used in collector, research.

Find roscoelite on the map

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