Lavendulan is a rare secondary copper arsenate prized by micromount collectors for its vibrant, electric blue to lavender-blue color. It typically forms delicate crusts, botryoidal aggregates, or radial sprays within the oxidized zones of copper-arsenic hydrothermal veins.
Is this lavendulan?
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 lavendulan with a known reference. Lavendulan sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Lavendulan leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Lavendulan typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: lavender-blue, bright blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: crusts, acicular sprays, radiating tufts.
Often confused with
Lavendulan vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Lavendulan and silky on Cyanotrichite.
How to tell apart: Streak differs, so Lavendulan leaves pale blue, Strashimirite leaves white; luster reads vitreous on Lavendulan and pearly on Strashimirite.
How to tell apart: Streak differs, so Lavendulan leaves pale blue, Tyrolite leaves pale green; luster reads vitreous on Lavendulan and pearly on Tyrolite.
Often found alongside lavendulan
Minerals reported to co-occur with lavendulan. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCaCu₅(AsO₄)₄Cl·5H₂O
- Mohs hardness
- 2.5
- Density
- 3.3 g/cm³
- Colors
- Streak
- Pale Blue
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Crusts, Acicular Sprays, Radiating Tufts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Arsenic-rich Base Metal Deposits
- Typical price
- $50-500 depending on specimen quality and matrix
Where rockhounds find lavendulan
Classic worldwide localities
- Jáchymov, Czech Republic
- Annaberg-Buchholz, Germany
- Cap Garonne, France
- Laurion, Greece
Field-hunting tip
Look in oxidized zones of arsenic-rich base metal deposits country, the host setting where lavendulan typically forms. If you start seeing malachite, azurite, cornubite in float, you are in the right ground. Field specimens usually show a crusts, acicular sprays, radiating tufts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find lavendulan on the map
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