Grantsite is an extremely rare hydrated sodium-uranium-vanadium mineral primarily found in the uranium-bearing sandstones of the Colorado Plateau. It usually appears as massive, earthy, yellow-colored crusts or coatings, making it difficult to distinguish visually from associated minerals like tyuyamunite without X-ray diffraction analysis.

Hardness

2-3

Mohs

Luster

Earthy

Streak

Yellow

Transparency

Opaque

mineralrare

Grantsite

Hardness: 2-3
Luster: Earthy
Streak: Yellow
Transparency: Opaque

Is this grantsite?

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 grantsite with a known reference. Grantsite 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. Grantsite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Grantsite typically shows a earthy luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-orange, brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: massive.

Often confused with

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

mineral

Carnotite

Mohs 2

How to tell apart: Luster reads earthy on Grantsite and dull on Carnotite.

How to tell apart: Luster reads earthy on Grantsite and pearly on Tyuyamunite.

Compare →

Often found alongside grantsite

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

All properties

Chemical formula: Na₄(V,U)₄O₁₂·10H₂O
Mohs hardness: 2-3
Density: 3.5-4 g/cm³
Colors: Yellow Yellow-orange Brown
Streak: Yellow
Luster: Earthy
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Massive
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Sandstone
Typical price: $20-150 for small specimens

Where rockhounds find grantsite

Classic worldwide localities

Grants district, New Mexico, USA
Colorado Plateau, USA

Field-hunting tip

Look in sandstone country — that is the host setting where grantsite typically forms. If you start seeing tyuyamunite, gypsum, calcite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify grantsite?+

Mohs hardness is 2-3. It typically shows a earthy luster. The streak is yellow. Common colors include yellow, yellow-orange, brown.

Where is grantsite found?+

Notable localities include Grants district, New Mexico, USA; Colorado Plateau, USA.

How much is grantsite worth?+

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

Is grantsite safe to handle?+

This mineral is radioactive. It contains toxic constituents. Grantsite contains both uranium and vanadium; it is radioactive and poses health risks if dust is inhaled or ingested. Proper shielding and handling protocols for radioactive minerals must be followed. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like grantsite?+

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

What minerals are found with grantsite?+

Grantsite commonly co-occurs with Tyuyamunite, Gypsum, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does grantsite form in?+

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

What is grantsite used for?+

Grantsite is used in collector.

Find grantsite on the map

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