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 — Lavendulan leaves pale blue, Strashimirite leaves white; luster reads vitreous on Lavendulan and pearly on Strashimirite.
How to tell apart: Streak differs — 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 — that is 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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