Meridianiite is a rare magnesium sulfate hydrate that was first identified on Mars by the Opportunity rover before being confirmed on Earth. It typically forms in very cold, hydrated environments and is chemically unstable at room temperature, often dehydrating into epsomite or hexahydrite.
Is this meridianiite?
4-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 meridianiite with a known reference. Meridianiite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Match the color rangeCompare against the expected color range: white.
- 4Look at form & habitCrystal system: triclinic. Typical habit: prismatic crystals, granular aggregates, crusts.
Often confused with
Meridianiite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside meridianiite
Minerals reported to co-occur with meridianiite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgSO₄·11H₂O
- Mohs hardness
- 2
- Density
- 1.507 g/cm³
- Colors
- Streak
- White
- Transparency
- Transparent to translucent
- Crystal system
- Triclinic
- Crystal habit
- Prismatic crystals, granular aggregates, crusts
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector, Scientific
- Host rock
- In a pocket near the surface of a frozen pond that allowed evaporation, concentration of dissolved matter, and crystallization at temperatures well below the freezing point of water
Where rockhounds find meridianiite
Classic worldwide localities
- Basque claims, near Ashcroft, central British Columbia, Canada
- Found in inclusions in sea ice from Saroma Lake, northeastern shore of Hokkaido Island, ~30 km from Abashiri City, Japan and at Dome Fuji Station, East Antarctica at the 3810 m asl summit of the East Dronning Maud Land Plateau
Field-hunting tip
Where it forms: In a pocket near the surface of a frozen pond that allowed evaporation, concentration of dissolved matter, and crystallization at temperatures well below the freezing point of water. If you start seeing ice in float, you are in the right ground. Typical habit: prismatic crystals, granular aggregates, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify meridianiite?+
Where is meridianiite found?+
What rocks look like meridianiite?+
What minerals are found with meridianiite?+
What kind of rock does meridianiite form in?+
What is meridianiite used for?+
Find meridianiite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
