Sofiite is an extremely rare secondary zinc selenite mineral discovered in volcanic fumaroles. It typically forms thin, transparent tabular crystals that are delicate and easily damaged, making it a highly sought-after prize for specialized mineral collectors.

Hardness

1.5-2

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Sofiite

Hardness: 1.5-2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this sofiite?

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 sofiite with a known reference. Sofiite sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Sofiite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Sofiite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, colorless, pale yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, crusts, or radiating aggregates.

Often confused with

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

Often found alongside sofiite

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

All properties

Chemical formula: Zn₂SeO₃Cl₂
Mohs hardness: 1.5-2
Density: 4.56 g/cm³
Colors: Yellow Colorless Pale Yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Crusts, Or Radiating Aggregates
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector
Host rock: Fumarole Deposits
Typical price: $50-300 per specimen

Where rockhounds find sofiite

Classic worldwide localities

Tolbachik volcano, Kamchatka, Russia

Field-hunting tip

Look in fumarole deposits country — that is the host setting where sofiite typically forms. If you start seeing selenite, cotunnite, halite in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts, or radiating aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify sofiite?+

Mohs hardness is 1.5-2. It typically shows a vitreous luster. The streak is white. Common colors include yellow, colorless, pale yellow.

Where is sofiite found?+

Notable localities include Tolbachik volcano, Kamchatka, Russia.

How much is sofiite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is sofiite safe to handle?+

It contains toxic constituents. Contains selenium, which is toxic; wash hands thoroughly after handling and avoid inhalation of dust or ingestion. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like sofiite?+

Sofiite is most often confused with Klyuchevskite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with sofiite?+

Sofiite commonly co-occurs with selenite, cotunnite, halite, zincite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does sofiite form in?+

Sofiite typically forms in fumarole deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is sofiite used for?+

Sofiite is used in collector.

Find sofiite on the map

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