Saponite is a soft, clay-like magnesium smectite mineral that often forms waxy, soapy feeling masses in veins of basalt or ultramafic rocks. Collectors typically seek it in association with zeolites or other cavity-filling minerals where it forms compact, pale-colored crusts or nodules.
Is this saponite?
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 saponite with a known reference. Saponite sits at Mohs <1-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: greasy.
- 4Match the color rangeCompare against the expected color range: white, yellowish white, greenish white, reddish white, bluish white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, massive.
Often confused with
Saponite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads greasy on Saponite and pearly, greasy, dull on Talc.
How to tell apart: Luster reads greasy on Saponite and dull, earthy on Montmorillonite.
How to tell apart: Luster reads greasy on Saponite and pearly to dull earthy on Kaolinite.
Often found alongside saponite
Minerals reported to co-occur with saponite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,Na)₀.₃(Mg,Fe)₃(Si,Al)₄O₁₀(OH)₂·4H₂O
- Mohs hardness
- <1-2
- Density
- 2.24-2.30 g/cm³
- Streak
- White
- Luster
- Greasy
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Granular, massive
- Cleavage
- {001}, perfect
- Rarity
- Common
- Uses
- Industrial, Collector
- Host rock
- Hydrothermally deposited in mineralized veins and in vesicles in basalt
Where rockhounds find saponite
Classic worldwide localities
- Kearsarge and Ahmeek mines, Keweenaw Peninsula, Houghton Co., Michigan, USA
- Between Pigeon Point and Fond du Lac, north shore of Lake Superior, Cook Co., Minnesota, USA
- Milford, Beaver Co., Utah, USA
- Ballarat, Inyo Co., California, USA
- Lizard, Cornwall, England
- Allt Ribhein, Fiskavaig Bay, Isle of Skye, Scotland
Field-hunting tip
Where it forms: Hydrothermally deposited in mineralized veins and in vesicles in basalt. If you start seeing celadonite, chlorite, copper in float, you are in the right ground. Typical habit: granular, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify saponite?+
Where is saponite found?+
What rocks look like saponite?+
What minerals are found with saponite?+
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Find saponite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
