Santaclaraite is a rare manganese silicate mineral primarily found in the metamorphosed chert-shale sequence of the Santa Clara Mine. It usually forms as attractive orange-colored fibrous or acicular aggregates that can be visually distinguished from the more common rhodonite by its distinct crystal habit and occurrence.
Is this santaclaraite?
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 santaclaraite with a known reference. Santaclaraite sits at Mohs 6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale pink.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: light pink, reddish orange.
- 5Look at form & habitCrystal system: triclinic. Typical habit: fibrous aggregates, radiating needles.
Often confused with
Santaclaraite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside santaclaraite
Minerals reported to co-occur with santaclaraite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMn₄Si₅O₁₄(OH)₂·H₂O
- Mohs hardness
- 6.5
- Density
- 3.31 g/cm³
- Colors
- Streak
- Pale pink
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Fibrous aggregates, radiating needles
- Cleavage
- Good on {100} and {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As cross-fiber veins and irregular masses in manganese-oxide-stained chert and quartz
Where rockhounds find santaclaraite
Classic worldwide localities
- Pennsylvania mine, SW side of San Antonio Valley, 4 miles ENE of Mount Hamilton, Santa Clara Co., California, USA (type locality)
Field-hunting tip
Where it forms: As cross-fiber veins and irregular masses in manganese-oxide-stained chert and quartz. If you start seeing calcite, quartz, barite in float, you are in the right ground. Typical habit: fibrous aggregates, radiating needles. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify santaclaraite?+
Where is santaclaraite found?+
What rocks look like santaclaraite?+
What minerals are found with santaclaraite?+
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What is santaclaraite used for?+
Find santaclaraite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
