Johannsenite is a manganese-rich member of the pyroxene group typically found in contact metamorphic skarn deposits. It usually forms as attractive, radial, or fibrous clusters in shades of light brown or green, and is highly sought after by systematic mineral collectors.
Is this johannsenite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch johannsenite with a known reference. Johannsenite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: brown, brownish black, greenish, gray, gray green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular, massive.
Often confused with
Johannsenite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside johannsenite
Minerals reported to co-occur with johannsenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMnSi₂O₆
- Mohs hardness
- 6
- Density
- 3.27-3.54 g/cm³
- Streak
- Greenish gray
- Luster
- Vitreous
- Transparency
- Translucent to opaque
- Crystal system
- Monoclinic
- Crystal habit
- Acicular, massive
- Cleavage
- Good on {110}, (110) ^ (110) ~87°; partings on {100}, {001}, and {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In metasomatized limestones and manganiferous skarns; in quartz or calcite veins cutting rhyolite
Where rockhounds find johannsenite
Classic worldwide localities
- Franklin, Sussex Co., New Jersey, USA
- Bohemia district, Lane Co., Oregon, USA
- Aravaipa district, Graham Co., Arizona, USA
- Empire Zinc Co. mine, Hanover, Grant Co., New Mexico, USA
- Tetela de Ocampo, Puebla, and Pachuca, Hidalgo, Mexico
- Schio, Vicenza, and Campiglia, Tuscany, Italy
Field-hunting tip
Where it forms: In metasomatized limestones and manganiferous skarns; in quartz or calcite veins cutting rhyolite. If you start seeing rhodonite, manganese oxides in float, you are in the right ground. Typical habit: acicular, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify johannsenite?+
Where is johannsenite found?+
What rocks look like johannsenite?+
What minerals are found with johannsenite?+
What kind of rock does johannsenite form in?+
What is johannsenite used for?+
Find johannsenite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
