Earlandite is an extremely rare organic mineral found in marine sediments, specifically discovered in the Weddell Sea. It typically appears as small, dull-white, chalky-looking nodules or aggregates and is scientifically significant as a calcium citrate mineral formed through biological or chemical processes in seafloor deposits.
Is this earlandite?
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 earlandite with a known reference. Earlandite sits at Mohs 2-3, 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: dull.
- 4Match the color rangeCompare against the expected color range: white, light yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: nodular.
Often confused with
Earlandite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads dull on Earlandite and vitreous, pearly on {010} and some cleavages on Whewellite.
How to tell apart: Weddellite is the harder of the two (Mohs ~4 vs. 2-3); luster reads dull on Earlandite and vitreous on Weddellite.
Often found alongside earlandite
Minerals reported to co-occur with earlandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₃(C₆H₅O₇)₂·4H₂O
- Mohs hardness
- 2-3
- Density
- 1.80-1.95 g/cm³
- Colors
- Streak
- White
- Luster
- Dull
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Nodular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In unconsolidated ocean floor sediment at 2580 m depth
Where rockhounds find earlandite
Classic worldwide localities
- Weddell Sea, near Antarctica
Field-hunting tip
Where it forms: In unconsolidated ocean floor sediment at 2580 m depth. If you start seeing quartz in float, you are in the right ground. Typical habit: nodular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify earlandite?+
Where is earlandite found?+
What rocks look like earlandite?+
What minerals are found with earlandite?+
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Find earlandite on the map
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