Rossite is a rare vanadium mineral that typically forms as yellow, transparent to translucent crusts or small tabular crystals in oxidized zones of uranium-vanadium deposits. It is unstable in dry air and often dehydrates to form its dimorph, metarossite. Collectors should store this mineral in a sealed container to prevent it from crumbling into a powdery form.

Hardness

2-3

Mohs

Luster

Vitreous to somewhat pearly

Streak

Yellow

Transparency

Transparent

mineralrare

Rossite

Hardness: 2-3
Luster: Vitreous to somewhat pearly
Streak: Yellow
Transparency: Transparent

Is this rossite?

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 rossite with a known reference. Rossite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to somewhat pearly.
4
Match the color range
Compare against the expected color range: yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, crusts, efflorescences.

Often confused with

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

mineral

Metarossite

Mohs 1-2

How to tell apart: Luster reads vitreous to somewhat pearly on Rossite and dull to pearly on Metarossite.

How to tell apart: Streak differs, so Rossite leaves yellow, Sherwoodite leaves pale blue.

Compare →

Often found alongside rossite

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

All properties

Chemical formula: CaV₂O₆·4H₂O
Mohs hardness: 2-3
Density: 2.45 g/cm³
Colors: Yellow
Streak: Yellow
Luster: Vitreous to somewhat pearly
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular crystals, crusts, efflorescences
Cleavage: One direction, prominent
Rarity: Rare
Uses: Collector
Host rock: In veinlets in carnotite-bearing sandstone (Bull Pen Canyon, Colorado, USA)

Where rockhounds find rossite

Classic worldwide localities

Yellow Cat Wash, Thompsons district, Grand Co., Utah, USA
Mesa No. 1 mine, Lukachukai Mountains, Arizona, USA
Malargüe district, Mendoza Province, Argentina

Field-hunting tip

Where it forms: In veinlets in carnotite-bearing sandstone (Bull Pen Canyon, Colorado, USA). If you start seeing metarossite, carnotite, gypsum in float, you are in the right ground. Typical habit: tabular crystals, crusts, efflorescences. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify rossite?+

Mohs hardness is 2-3. Luster: vitreous to somewhat pearly. The streak is yellow. Common colors include yellow.

Where is rossite found?+

Notable localities include Yellow Cat Wash, Thompsons district, Grand Co., Utah, USA; Mesa No. 1 mine, Lukachukai Mountains, Arizona, USA; Malargüe district, Mendoza Province, Argentina.

Is rossite safe to handle?+

Rossite contains vanadium. Contains vanadium, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust when cleaning specimens.

What rocks look like rossite?+

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

What minerals are found with rossite?+

Rossite commonly co-occurs with Metarossite, Carnotite, Gypsum, Huemulite, Hummerite, Thenardite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does rossite form in?+

Where it forms: In veinlets in carnotite-bearing sandstone (Bull Pen Canyon, Colorado, USA). Working float back to the host body is the standard way to chase a fresh occurrence.

What is rossite used for?+

Rossite is used in collector.

Find rossite on the map

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