Bobcookite is a rare sodium aluminum uranium sulfate, typically lime-green to greenish yellow. It was approved as a distinct mineral species in 2014. It was first described from Blue Lizard mine, Red Canyon, White Canyon district, San Juan County, Utah, USA.

Hardness

Mohs

Luster

Vitreous

Streak

Very Pale Yellowish Green

Transparency

Transparent

mineralrare

Bobcookite

Hardness: 2
Luster: Vitreous
Streak: Very Pale Yellowish Green
Transparency: Transparent

Is this bobcookite?

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 bobcookite with a known reference. Bobcookite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Bobcookite leaves a very pale yellowish green streak.
3
Read the luster
Hold the specimen under a strong light. Bobcookite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: lime-green, greenish yellow.
5
Look at form & habit
Crystal system: triclinic. Typical habit: acicular to fibrous sprays or crusts.

Often found alongside bobcookite

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

All properties

Chemical formula: NaAl(UO₂)₂(SO₄)₄·18H₂O
Mohs hardness: 2
Density: 2.669 g/cm³
Colors: Lime-green Greenish Yellow
Streak: Very Pale Yellowish Green
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Acicular to Fibrous Sprays or Crusts
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Igneous Intrusions

Where rockhounds find bobcookite

Classic worldwide localities

Blue Lizard mine, Utah, USA

Field-hunting tip

Look in alkaline igneous intrusions country, the host setting where bobcookite typically forms. If you start seeing sodalite, analcime, natrolite in float, you are in the right ground. Field specimens usually show a acicular to fibrous sprays or crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify bobcookite?+

Mohs hardness is 2. It typically shows a vitreous luster. The streak is very pale yellowish green. Common colors include lime-green, greenish yellow.

Where is bobcookite found?+

Notable localities include Blue Lizard mine, Utah, USA.

Is bobcookite safe to handle?+

This mineral is radioactive. Contains uranium and is radioactive; store it apart from other specimens. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What minerals are found with bobcookite?+

Bobcookite commonly co-occurs with sodalite, analcime, natrolite, microcline, leifite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does bobcookite form in?+

Bobcookite typically forms in alkaline igneous intrusions. Working float back to the host body is the standard way to chase a fresh occurrence.

What is bobcookite used for?+

Bobcookite is used in collector.

Find bobcookite on the map

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