Tungusite is a rare phyllosilicate mineral typically found in the amygdaloidal cavities of basaltic rocks. It is characterized by its delicate, platy to foliated habit and pearly luster, often forming radiating clusters that resemble small rosettes.
Is this tungusite?
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 tungusite with a known reference. Tungusite sits at Mohs ~2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light green.
- 3Read the lusterHold the specimen under a strong light. Luster: slightly pearly on flakes.
- 4Match the color rangeCompare against the expected color range: grass green, yellow green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: flakes.
Often confused with
Tungusite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tungusite leaves light green, Celadonite leaves greenish white; luster reads slightly pearly on flakes on Tungusite and dull on Celadonite.
How to tell apart: Prehnite is the harder of the two (Mohs 6-6.5 vs. ~2); streak differs, so Tungusite leaves light green, Prehnite leaves white; luster reads slightly pearly on flakes on Tungusite and vitreous, weak pearly on {001} on Prehnite.
How to tell apart: Streak differs, so Tungusite leaves light green, Chlorite leaves white; luster reads slightly pearly on flakes on Tungusite and pearly on Chlorite.
Often found alongside tungusite
Minerals reported to co-occur with tungusite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₁₄Fe₉Si₂₄O₆₀(OH)₂₂
- Mohs hardness
- ~2
- Density
- 2.59 g/cm³
- Colors
- Streak
- Light green
- Luster
- Slightly pearly on flakes
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Flakes
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral forming crusts lining cavities and amygdules in hydrothermally altered basalts
Where rockhounds find tungusite
Classic worldwide localities
- Found along the Lower Tunguska River, near Tura, central Siberia, Russia
Field-hunting tip
Where it forms: A secondary mineral forming crusts lining cavities and amygdules in hydrothermally altered basalts. If you start seeing analcime, apophyllite, gyrolite in float, you are in the right ground. Typical habit: flakes. Train your eye for that shape before scanning the outcrop.
Common questions
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Find tungusite on the map
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