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?
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 ferromerrillite with a known reference. Ferromerrillite sits at Mohs ~5, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: colorless.
- 4Look 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.
All properties
- Chemical formula
- Ca₉NaFe²⁺(PO₄)₇
- Mohs hardness
- ~5
- Density
- 3.14 g/cm³
- Colors
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Trigonal
- Crystal habit
- Anhedral grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An accessory phase in the basaltic and olivine-phyric subgroups of shergottite meteorites
Where rockhounds find ferromerrillite
Classic worldwide localities
- Shergotty meteorite, Gaya, Bihar, India (type locality)
Field-hunting tip
Where it forms: An accessory phase in the basaltic and olivine-phyric subgroups of shergottite meteorites. If you start seeing clinopyroxene, maskelynite in float, you are in the right ground. Typical habit: anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferromerrillite?+
Where is ferromerrillite found?+
What rocks look like ferromerrillite?+
What minerals are found with ferromerrillite?+
What kind of rock does ferromerrillite form in?+
What is ferromerrillite used for?+
Find ferromerrillite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
