Swartzite is a rare uranyl carbonate mineral that typically forms distinct, thin tabular crystals with a bright yellow-green color. Collectors prize it for its intense green fluorescence under ultraviolet light. It is primarily found as a secondary mineral in oxidized uranium deposits in the western United States.

Hardness

2.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Swartzite

Hardness: 2.5
Luster: Vitreous
Streak: White
Transparency: Transparent

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Is this swartzite?

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 swartzite with a known reference. Swartzite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: 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: yellowish, yellowish white, light green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: efflorescences, prismatic.

Often confused with

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

How to tell apart: Streak differs, so Swartzite leaves white, Liebigite leaves yellow white.

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Often found alongside swartzite

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

All properties

Chemical formula: CaMg(UO₂)(CO₃)₃·12H₂O
Mohs hardness: 2.5
Density: 2.3 g/cm³
Colors: Yellowish Yellowish white Light green
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Efflorescences, prismatic
Cleavage: Perfect
Fluorescence: Bright green under SW and LW UV
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral in oxidized portions of a polymetallic sulfide deposit, the source of uranium undetermined

Where rockhounds find swartzite

Classic worldwide localities

Hillside mine, Yavapai County, Arizona, USA (type locality)

Field-hunting tip

Where it forms: A secondary mineral in oxidized portions of a polymetallic sulfide deposit, the source of uranium undetermined. If you start seeing gypsum, schröckingerite, andersonite in float, you are in the right ground. Typical habit: efflorescences, prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify swartzite?+

Mohs hardness is 2.5. Luster: vitreous. The streak is white. Common colors include yellowish, yellowish white, light green.

Where is swartzite found?+

Notable localities include Hillside mine, Yavapai County, Arizona, USA (type locality).

Is swartzite safe to handle?+

Swartzite contains uranium or thorium and calls for real care. Contains uranium and is radioactive; handle with care, store in a lead-lined container, and wash hands thoroughly after handling.

What rocks look like swartzite?+

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

What minerals are found with swartzite?+

Swartzite commonly co-occurs with Gypsum, Schröckingerite, Andersonite, Bayleyite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does swartzite form in?+

Where it forms: A secondary mineral in oxidized portions of a polymetallic sulfide deposit, the source of uranium undetermined. Working float back to the host body is the standard way to chase a fresh occurrence.

What is swartzite used for?+

Swartzite is used in collector.

Find swartzite on the map

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