Molinelloite is a rare copper-magnesium silicate mineral typically found as small, deep blue acicular sprays within manganese mines. It is highly sought after by collectors for its brilliant color and delicate crystal habits, usually occurring in small cavities within chert or manganese ores.
Is this molinelloite?
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 molinelloite with a known reference. Molinelloite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Molinelloite leaves a pale blue streak.
- 3Read the lusterHold the specimen under a strong light. Molinelloite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: blue, deep blue.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular or prismatic crystals, commonly in radial sprays.
Often confused with
Molinelloite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Molinelloite leaves pale blue, Chrysocolla leaves white.
How to tell apart: Streak differs — Molinelloite leaves pale blue, Shattuckite leaves blue; luster reads vitreous on Molinelloite and dull on Shattuckite.
Often found alongside molinelloite
Minerals reported to co-occur with molinelloite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₄Mg(Si₂O₇)(OH)₆
- Mohs hardness
- 3
- Density
- 3.51 g/cm³
- Streak
- Pale Blue
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular or Prismatic Crystals, Commonly in Radial Sprays
- Cleavage
- Good in One Direction
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Manganese-rich Cherts and Metamorphic Rocks
- Typical price
- $50-300 per micro-specimen
Where rockhounds find molinelloite
Classic worldwide localities
- Molinello Mine, Italy
- Gambatesa Mine, Italy
Field-hunting tip
Look in manganese-rich cherts and metamorphic rocks country — that is the host setting where molinelloite typically forms. If you start seeing braunite, quartz, calcite in float, you are in the right ground. Field specimens usually show a acicular or prismatic crystals, commonly in radial sprays habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find molinelloite on the map
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