Epidote-(Sr) is a rare strontium-bearing member of the epidote group, often indistinguishable from standard epidote without chemical analysis. It typically forms in metamorphic environments where strontium-rich fluids are present, frequently occurring as small, prismatic, yellowish-brown crystals.

Hardness

Mohs

Transparency

Translucent

mineralrareEpidote Group family

Epidote-(Sr)

Hardness: 6.5
Transparency: Translucent

Is this epidote-(sr)?

3-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch epidote-(sr) with a known reference. Epidote-(Sr) sits at Mohs 6.5, softer than the next harder reference, harder than the previous one.
2
Match the color range
Compare against the expected color range: brown, pale reddish brown.
3
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals, granular.

Often confused with

Epidote-(Sr) vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside epidote-(sr)

Minerals reported to co-occur with epidote-(sr). Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: CaSrAl₂Fe³⁺(Si₂O₇)(SiO₄)O(OH)
Mohs hardness: 6.5
Density: 3.74 g/cm³
Colors: BrownPale reddish brown
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic crystals, granular
Cleavage: Perfect on {001}
Rarity: Rare
Uses: Collector
Host rock: A late-stage hydrothermal vein mineral in a tinzenite deposit in metachert (Nagakawara deposit) and in piemontite breccias (Hohnomori deposit)

Where rockhounds find epidote-(sr)

Classic worldwide localities

Nagakawara and Hohnomori deposits, Ananai mine, Kochi Prefecture, Japan

Field-hunting tip

Where it forms: A late-stage hydrothermal vein mineral in a tinzenite deposit in metachert (Nagakawara deposit) and in piemontite breccias (Hohnomori deposit). If you start seeing calcite, tinzenite, piemontite- in float, you are in the right ground. Typical habit: prismatic crystals, granular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify epidote-(sr)?+

Mohs hardness is 6.5. Common colors include brown, pale reddish brown.

Where is epidote-(sr) found?+

Notable localities include Nagakawara and Hohnomori deposits, Ananai mine, Kochi Prefecture, Japan.

What rocks look like epidote-(sr)?+

Epidote-(Sr) is most often confused with Epidote, Clinozoisite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with epidote-(sr)?+

Epidote-(Sr) commonly co-occurs with Calcite, Tinzenite, Piemontite-. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does epidote-(sr) form in?+

Where it forms: A late-stage hydrothermal vein mineral in a tinzenite deposit in metachert (Nagakawara deposit) and in piemontite breccias (Hohnomori deposit). Working float back to the host body is the standard way to chase a fresh occurrence.

What is epidote-(sr) used for?+

Epidote-(Sr) is used in collector.

Find epidote-(sr) on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.