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. Streak: light blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, waxy, satiny in aggregates.
- 4Match the color rangeCompare against the expected color range: lavender blue, blue, greenish blue.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: botryoidal, encrustations.
Often confused with
Lavendulan vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Lavendulan leaves light blue, Cyanotrichite leaves pale blue; luster reads vitreous, waxy, satiny in aggregates on Lavendulan and silky on Cyanotrichite.
How to tell apart: Streak differs, so Lavendulan leaves light blue, Strashimirite leaves pale green; luster reads vitreous, waxy, satiny in aggregates on Lavendulan and pearly to greasy on Strashimirite.
How to tell apart: Streak differs, so Lavendulan leaves light blue, Tyrolite leaves pale green or pale blue.
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
- 3.54 g/cm³
- Colors
- Streak
- Light blue
- Luster
- Vitreous, waxy, satiny in aggregates
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Botryoidal, encrustations
- Cleavage
- Good on {010}; distinct on {100} and {001}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- A rare secondary mineral in the oxidized zone of some copper deposits
Where rockhounds find lavendulan
Classic worldwide localities
- Gold Hill, Tooele Co., Utah, USA
- Annaberg, Saxony, Germany
- Jáchymov (Joachimsthal), Czech Republic
- Littleham Cove area, Budleigh Salterton, Devon, England
- Cligga mine, Perranzabuloe, and the Pentireglaze mine, Cornwall, England
- Bunmahon, Co. Waterford, Ireland
Field-hunting tip
Where it forms: A rare secondary mineral in the oxidized zone of some copper deposits. If you start seeing erythrite, cuprite, malachite in float, you are in the right ground. Typical habit: botryoidal, encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify lavendulan?+
Where is lavendulan found?+
Is lavendulan safe to handle?+
What rocks look like lavendulan?+
What minerals are found with lavendulan?+
What kind of rock does lavendulan form in?+
What is lavendulan used for?+
Find lavendulan on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
