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, so Roscoelite leaves light green, Fuchsite leaves white.

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

Compare →

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, 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.