Ferromerrillite is an extremely rare phosphate mineral primarily identified in extraterrestrial samples such as Martian and lunar meteorites. It typically occurs as small, anhedral grains within the crystalline matrix of achondrites, appearing colorless to pale yellow under petrographic study.
Is this ferromerrillite?
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 ferromerrillite with a known reference. Ferromerrillite sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferromerrillite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Ferromerrillite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: anhedral grains.
Often confused with
Ferromerrillite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ferromerrillite
Minerals reported to co-occur with ferromerrillite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₉NaFe²⁺(PO₄)₇
- Mohs hardness
- 5
- Density
- 3.5-3.6 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Achondritic Meteorites
- Typical price
- $100-500 per micro-mount specimen
Where rockhounds find ferromerrillite
Classic worldwide localities
- Moon (lunar meteorites)
- Martian meteorites
- angrite meteorites
Field-hunting tip
Look in achondritic meteorites country — that is the host setting where ferromerrillite typically forms. If you start seeing olivine, pyroxene, plagioclase in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferromerrillite?+
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How much is ferromerrillite worth?+
What rocks look like ferromerrillite?+
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Find ferromerrillite on the map
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