Tschermakite is a complex calcium-magnesium-aluminum silicate belonging to the amphibole group, typically found in high-grade metamorphic rocks. Collectors often identify it by its prismatic, dark-colored crystalline habit and its occurrence within metamorphic terrains like skarns and amphibolites.
Is this tschermakite?
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 tschermakite with a known reference. Tschermakite sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: black, green, dark green.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, massive, granular.
Often confused with
Tschermakite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tschermakite leaves greenish white, Hornblende leaves grayish-white.
How to tell apart: Streak differs, so Tschermakite leaves greenish white, Edenite leaves white.
How to tell apart: Streak differs, so Tschermakite leaves greenish white, Pargasite leaves white.
Often found alongside tschermakite
Minerals reported to co-occur with tschermakite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂(Mg₃Al₂)(Si₆Al₂)O₂₂(OH)₂
- Mohs hardness
- 5-6
- Density
- 3.14-3.35 g/cm³
- Colors
- Streak
- Greenish white
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, massive, granular
- Cleavage
- Perfect on {110}, intersecting at 56° and 124°; partings on {100}, {001}
- Rarity
- Uncommon
- Uses
- Collector, Petrological studies
- Host rock
- From eclogites and other ultramafic igneous rocks, and in medium- to high-grade metamorphic rocks, typically amphibolites
Where rockhounds find tschermakite
Classic worldwide localities
- Hurry Inlet, Fisken½sset, Greenland
- Glenelg and Knockormal, Ayrshire, Scotland
- Lake Kutemajärvi, Orivesi, and Perniö, Finland
- Le Viala du Tarn, Aveyron, France
- Central Bug region, Ukraine
Field-hunting tip
Where it forms: From eclogites and other ultramafic igneous rocks, and in medium- to high-grade metamorphic rocks, typically amphibolites. If you start seeing kyanite, garnet in float, you are in the right ground. Typical habit: prismatic crystals, massive, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tschermakite?+
Where is tschermakite found?+
What rocks look like tschermakite?+
What minerals are found with tschermakite?+
What kind of rock does tschermakite form in?+
What is tschermakite used for?+
Find tschermakite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
