Piemontite-(Sr) is a rare member of the epidote group characterized by significant strontium substitution. It typically presents as striking reddish-brown prismatic crystals or fibrous aggregates, often found in manganese-enriched metamorphic environments.
Is this piemontite-(sr)?
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 piemontite-(sr) with a known reference. Piemontite-(Sr) sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: purple brown.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic.
Often confused with
Piemontite-(Sr) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Piemontite-(Sr) leaves purple brown, Piemontite leaves reddish.
How to tell apart: Streak differs, so Piemontite-(Sr) leaves purple brown, Epidote leaves grayish white.
How to tell apart: Streak differs, so Piemontite-(Sr) leaves purple brown, Allanite leaves gray; luster reads vitreous on Piemontite-(Sr) and submetallic on Allanite.
Often found alongside piemontite-(sr)
Minerals reported to co-occur with piemontite-(sr). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSrAl₂Mn³⁺(SiO₄)(Si₂O₇)O(OH)
- Mohs hardness
- 6
- Density
- 3.65-3.73 g/cm³
- Colors
- Streak
- Purple brown
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As veinlets in a low-temperature metamorphosed manganese ore deposit
Where rockhounds find piemontite-(sr)
Classic worldwide localities
- From the Molinello and Cassagna manganese mines, near Chiavari, Val Graveglia, Liguria, Italy (type locality)
Field-hunting tip
Where it forms: As veinlets in a low-temperature metamorphosed manganese ore deposit. If you start seeing quartz, calcite, manganese minerals in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify piemontite-(sr)?+
Where is piemontite-(sr) found?+
What rocks look like piemontite-(sr)?+
What minerals are found with piemontite-(sr)?+
What kind of rock does piemontite-(sr) form in?+
What is piemontite-(sr) used for?+
Find piemontite-(sr) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
