Schoenfliesite is a rare magnesium-tin hydroxide mineral that typically forms small, sharp octahedral crystals. It is primarily found in hydrothermal tin deposits where it occurs as a secondary mineral alongside other tin-bearing species like cassiterite.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareStottite Group family

Schoenfliesite

Hardness: ~4
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this schoenfliesite?

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 schoenfliesite with a known reference. Schoenfliesite sits at Mohs ~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: reddish brown.
5
Look at form & habit
Crystal system: cubic. Typical habit: fibrous, prismatic.

Often confused with

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

mineral

Stottite

Mohs 4.5

How to tell apart: Streak differs, so Schoenfliesite leaves white, Stottite leaves grayish white; luster reads vitreous on Schoenfliesite and resinous to adamantine, greasy on cleavages on Stottite.

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Often found alongside schoenfliesite

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

All properties

Chemical formula: MgSn(OH)₆
Mohs hardness: ~4
Density: 3.483 g/cm³
Colors: Reddish brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Cubic
Crystal habit: Fibrous, prismatic
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A late-stage hydrothermal alteration product of hulsite in a boron-metasomatized limestone near the contact with a granite intrusive (Brooks Range, Alaska, USA)

Where rockhounds find schoenfliesite

Classic worldwide localities

Northwest flank of Brooks Mountain, Seward Peninsula, Alaska, USA
Pitkäranta district, Lake Ladoga, Karelia, Russia
Damoshan deposit, Gejiu tin district, Yunnan Province, China
Sungai Gow, Pahang, Malaysia

Field-hunting tip

Where it forms: A late-stage hydrothermal alteration product of hulsite in a boron-metasomatized limestone near the contact with a granite intrusive (Brooks Range, Alaska, USA). If you start seeing hulsite, goethite, maghemite in float, you are in the right ground. Typical habit: fibrous, prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify schoenfliesite?+

Mohs hardness is ~4. Luster: vitreous. The streak is white. Common colors include reddish brown.

Where is schoenfliesite found?+

Notable localities include Northwest flank of Brooks Mountain, Seward Peninsula, Alaska, USA; Pitkäranta district, Lake Ladoga, Karelia, Russia; Damoshan deposit, Gejiu tin district, Yunnan Province, China; Sungai Gow, Pahang, Malaysia.

What rocks look like schoenfliesite?+

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

What minerals are found with schoenfliesite?+

Schoenfliesite commonly co-occurs with Hulsite, Goethite, Maghemite, Cassiterite, Berborite, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does schoenfliesite form in?+

Where it forms: A late-stage hydrothermal alteration product of hulsite in a boron-metasomatized limestone near the contact with a granite intrusive (Brooks Range, Alaska, USA). Working float back to the host body is the standard way to chase a fresh occurrence.

What is schoenfliesite used for?+

Schoenfliesite is used in collector.

Find schoenfliesite on the map

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