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, 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.