Overite is a scarce phosphate mineral that typically forms as delicate, colorless to pale yellow blades or radial clusters. It is highly sought after by micromount collectors and is famously associated with the phosphate nodules found in the Fairfield vivianite locality of Utah.

Hardness

3.5-4

Mohs

Luster

Vitreous

Streak

White

Transparency

Semitransparent

mineralrare

Overite

Hardness: 3.5-4
Luster: Vitreous
Streak: White
Transparency: Semitransparent

No image

Is this overite?

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 overite with a known reference. Overite sits at Mohs 3.5-4, 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: colorless, light green.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: bladed crystals, radial aggregates, crusts.

Often confused with

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

How to tell apart: Crandallite is the harder of the two (Mohs 5 vs. 3.5-4).

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Often found alongside overite

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

All properties

Chemical formula: CaMgAl(PO₄)₂(OH)(H₂O)₄
Mohs hardness: 3.5-4
Density: 2.53 g/cm³
Colors: Colorless Light green
Streak: White
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Bladed crystals, radial aggregates, crusts
Cleavage: {010}, perfect; {100}, poor
Rarity: Rare
Uses: Collector
Host rock: In phosphate nodules (Fairfield, Utah, USA); in a complex granite pegmatite (Tanco pegmatite, Canada)

Where rockhounds find overite

Classic worldwide localities

Found at the Little Green Monster mine, Clay Canyon, about nine km west of Fairfield, Utah Co., Utah, USA
Tanco pegmatite, Bernic Lake, Manitoba, Canada

Field-hunting tip

Where it forms: In phosphate nodules (Fairfield, Utah, USA); in a complex granite pegmatite (Tanco pegmatite, Canada). If you start seeing variscite, apatite in float, you are in the right ground. Typical habit: bladed crystals, radial aggregates, crusts. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify overite?+

Mohs hardness is 3.5-4. Luster: vitreous. The streak is white. Common colors include colorless, light green.

Where is overite found?+

Notable localities include Found at the Little Green Monster mine, Clay Canyon, about nine km west of Fairfield, Utah Co., Utah, USA; Tanco pegmatite, Bernic Lake, Manitoba, Canada.

What rocks look like overite?+

Overite is most often confused with Montgomeryite, Variscite, Crandallite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with overite?+

Overite commonly co-occurs with Variscite, Apatite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does overite form in?+

Where it forms: In phosphate nodules (Fairfield, Utah, USA); in a complex granite pegmatite (Tanco pegmatite, Canada). Working float back to the host body is the standard way to chase a fresh occurrence.

What is overite used for?+

Overite is used in collector.

Find overite on the map

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