Ercitite is an extremely rare phosphate mineral discovered in complex granite pegmatites. It typically appears as small, thin, tabular crystals or radiating aggregates of yellow to brownish-yellow color often found associated with other secondary phosphate minerals.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

Beige

Transparency

Translucent

mineralrare

Ercitite

Hardness: 3-4
Luster: Vitreous
Streak: Beige
Transparency: Translucent

No image

Is this ercitite?

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 ercitite with a known reference. Ercitite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: beige.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: dark brown, black.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: lath, microscopic crystals.

Often confused with

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

mineral

Variscite

Mohs 4.5

How to tell apart: Streak differs, so Ercitite leaves beige, Variscite leaves white.

How to tell apart: Streak differs, so Ercitite leaves beige, Strengite leaves white.

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Often found alongside ercitite

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

All properties

Chemical formula: NaMn³⁺(PO₄)(OH)·2H₂O
Mohs hardness: 3-4
Density: 2.77 g/cm³
Colors: Dark brown Black
Streak: Beige
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Lath, microscopic crystals
Cleavage: Very good parallel {100} and {001}
Rarity: Rare
Uses: Collector
Host rock: Strongly oxidizing, low-temperature hydrothermal alteration

Where rockhounds find ercitite

Classic worldwide localities

Tanco pegmatite at Bernic Lake, southeastern Maitoba, Canada (type locality)

Field-hunting tip

Where it forms: Strongly oxidizing, low-temperature hydrothermal alteration. If you start seeing lithiophilite, lithiophosphate, collinsite in float, you are in the right ground. Typical habit: lath, microscopic crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ercitite?+

Mohs hardness is 3-4. Luster: vitreous. The streak is beige. Common colors include dark brown, black.

Where is ercitite found?+

Notable localities include Tanco pegmatite at Bernic Lake, southeastern Maitoba, Canada (type locality).

What rocks look like ercitite?+

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

What minerals are found with ercitite?+

Ercitite commonly co-occurs with Lithiophilite, Lithiophosphate, Collinsite, Fairfieldite, Whitlockite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ercitite form in?+

Where it forms: Strongly oxidizing, low-temperature hydrothermal alteration. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ercitite used for?+

Ercitite is used in collector.

Find ercitite on the map

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