Caminite is a rare magnesium sulfate hydroxide mineral formed primarily in hydrothermal vent settings on the ocean floor. It typically occurs as white to colorless platy crystals associated with anhydrite and metallic sulfides in deep-sea environments.

Hardness

3-3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Caminite

Hardness: 3-3.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this caminite?

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 caminite with a known reference. Caminite sits at Mohs 3-3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Caminite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Caminite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: platy crystals, crusts, or globular aggregates.

Often confused with

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

How to tell apart: Caminite is noticeably harder (Mohs 3-3.5 vs. 2).

Often found alongside caminite

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

All properties

Chemical formula: Mg(SO₄)₀.₃(OH)₁.₄
Mohs hardness: 3-3.5
Density: 2.8 g/cm³
Colors: White Colorless Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Platy Crystals, Crusts, Or Globular Aggregates
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Hydrothermal Vent Chimneys
Typical price: n/a

Where rockhounds find caminite

Classic worldwide localities

Dallaporta vent field, East Pacific Rise
Guaymas Basin, Gulf of California

Field-hunting tip

Look in hydrothermal vent chimneys country — that is the host setting where caminite typically forms. If you start seeing anhydrite, gypsum, pyrite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts, or globular aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify caminite?+

Mohs hardness is 3-3.5. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, pale yellow.

Where is caminite found?+

Notable localities include Dallaporta vent field, East Pacific Rise; Guaymas Basin, Gulf of California.

How much is caminite worth?+

Typical asking prices fall in the range of n/a. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like caminite?+

Caminite is most often confused with Anhydrite, Gypsum, Bassanite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with caminite?+

Caminite commonly co-occurs with Anhydrite, Gypsum, Pyrite, Sphalerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does caminite form in?+

Caminite typically forms in hydrothermal vent chimneys. Working float back to the host body is the standard way to chase a fresh occurrence.

What is caminite used for?+

Caminite is used in collector.

Find caminite on the map

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