Okhotskite is a rare member of the pumpellyite group, distinct for its high manganese content which gives it a characteristic reddish-brown color. It is typically found in manganese-rich metamorphic environments and forms small prismatic or acicular crystals.

Hardness

Mohs

Luster

Vitreous

Streak

Pale orange

Transparency

Transparent

mineralrarePumpellyite Group family

Okhotskite

Hardness: 6
Luster: Vitreous
Streak: Pale orange
Transparency: Transparent

Is this okhotskite?

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 okhotskite with a known reference. Okhotskite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale orange.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: deep orange.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic to acicular crystals, fibrous aggregates.

Often confused with

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

mineral

Sursassite

Mohs 3

How to tell apart: Okhotskite is noticeably harder (Mohs 6 vs. 3); streak differs, so Okhotskite leaves pale orange, Sursassite leaves yellowish brown.

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Often found alongside okhotskite

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

All properties

Chemical formula: Ca₂MnMn₂(Si₂O₇)(SiO₄)(OH)₂·H₂O
Mohs hardness: 6
Density: 3.40 g/cm³
Colors: Deep orange
Streak: Pale orange
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Prismatic to acicular crystals, fibrous aggregates
Cleavage: One set observed in thin section
Rarity: Rare
Uses: Collector
Host rock: In network veinlets cutting hematite-rich ores

Where rockhounds find okhotskite

Classic worldwide localities

Kokuriki mine, at Hiyoshi, about 20 km north of Kitami City, Hokkaido, Japan

Field-hunting tip

Where it forms: In network veinlets cutting hematite-rich ores. If you start seeing hematite, quartz, piemontite in float, you are in the right ground. Typical habit: prismatic to acicular crystals, fibrous aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify okhotskite?+

Mohs hardness is 6. Luster: vitreous. The streak is pale orange. Common colors include deep orange.

Where is okhotskite found?+

Notable localities include Kokuriki mine, at Hiyoshi, about 20 km north of Kitami City, Hokkaido, Japan.

What rocks look like okhotskite?+

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

What minerals are found with okhotskite?+

Okhotskite commonly co-occurs with Hematite, Quartz, Piemontite, Neotocite, Bementite, Apatite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does okhotskite form in?+

Where it forms: In network veinlets cutting hematite-rich ores. Working float back to the host body is the standard way to chase a fresh occurrence.

What is okhotskite used for?+

Okhotskite is used in collector.

Find okhotskite on the map

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