Urea is a rare, naturally occurring organic mineral typically found as a result of organic activity in guano deposits within caves. It forms tetragonal crystals that are highly water-soluble, making it a very difficult species to preserve in typical collection environments without controlled humidity.

Hardness

Mohs

Luster

Vitreous

Streak

Yellow white

Transparency

Semitransparent

mineralrare

Urea

Also: carbamide

Hardness: 2
Luster: Vitreous
Streak: Yellow white
Transparency: Semitransparent

Is this urea?

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 urea with a known reference. Urea 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. Streak: yellow white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: light brown, light yellow.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: prismatic crystals.

Often confused with

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

mineral

Nitratine

Mohs 1.5-2

How to tell apart: Streak differs, so Urea leaves yellow white, Nitratine leaves white.

How to tell apart: Streak differs, so Urea leaves yellow white, Halite leaves white.

Compare →

Often found alongside urea

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

All properties

Chemical formula: CO(NH₂)₂
Mohs hardness: 2
Density: 1.33 g/cm³
Colors: Light brown Light yellow
Streak: Yellow white
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Tetragonal
Crystal habit: Prismatic crystals
Cleavage: Poor
Rarity: Rare
Uses: Industrial, Scientific research, Collector
Host rock: Derived from bat guano and urine, stable only under very arid conditions

Where rockhounds find urea

Classic worldwide localities

Toppin Hill, near Lake Rason, about 320 km northeast of Kalgoorlie, and in Wilgie Mia Cave, Western Australia

Field-hunting tip

Where it forms: Derived from bat guano and urine, stable only under very arid conditions. If you start seeing ammonian aphthitalite, weddellite, phosphammite in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify urea?+

Mohs hardness is 2. Luster: vitreous. The streak is yellow white. Common colors include light brown, light yellow.

Where is urea found?+

Notable localities include Toppin Hill, near Lake Rason, about 320 km northeast of Kalgoorlie, and in Wilgie Mia Cave, Western Australia.

What rocks look like urea?+

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

What minerals are found with urea?+

Urea commonly co-occurs with Ammonian aphthitalite, Weddellite, Phosphammite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does urea form in?+

Where it forms: Derived from bat guano and urine, stable only under very arid conditions. Working float back to the host body is the standard way to chase a fresh occurrence.

What is urea used for?+

Urea is used in industrial, scientific research, collector.

Find urea on the map

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