Calcioferrite is a rare secondary phosphate mineral typically found as a result of the alteration of triphylite in pegmatites. Collectors should look for its characteristic pale yellow to brown tabular crystals or delicate rosettes often associated with other iron-phosphate minerals.
Is this calcioferrite?
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 calcioferrite with a known reference. Calcioferrite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: sulfur-yellow to white.
- 3Read the lusterHold the specimen under a strong light. Luster: pearly on cleavages.
- 4Match the color rangeCompare against the expected color range: yellow, greenish yellow, yellow green, yellowish white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: foliated, reniform.
Often confused with
Calcioferrite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Calcioferrite leaves sulfur-yellow to white, Mitridatite leaves olive-green; luster reads pearly on cleavages on Calcioferrite and dull, earthy to resinous on Mitridatite.
How to tell apart: Streak differs, so Calcioferrite leaves sulfur-yellow to white, Vivianite leaves white, altering to dark blue, brown; luster reads pearly on cleavages on Calcioferrite and vitreous, pearly on the cleavage, dull when earthy on Vivianite.
Often found alongside calcioferrite
Minerals reported to co-occur with calcioferrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₄MgFe₄(PO₄)₆(OH)₄·12H₂O
- Mohs hardness
- 2.5
- Density
- 2.51-2.53 g/cm³
- Streak
- Sulfur-yellow to white
- Luster
- Pearly on cleavages
- Transparency
- Transparent to translucent, opaque if massive
- Crystal system
- Monoclinic
- Crystal habit
- Foliated, reniform
- Cleavage
- One, perfect, parallel foliation; another, interrupted, perpendicular to the first; a third, also interrupted, oblique to the first
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As nodules in a bed of Tertiary clay (The Battenberg, Germany); in phosphatic clay (Moculta quarry, Australia)
Where rockhounds find calcioferrite
Classic worldwide localities
- Battenberg, and from Hagendorf, Bavaria, Germany
- Sal Island, Cape Verde Islands
- Moculta phosphate quarry, northeast of Angaston, South Australia
- An undefined locality in the Kara- Tau Range, Kazakhstan
Field-hunting tip
Where it forms: As nodules in a bed of Tertiary clay (The Battenberg, Germany); in phosphatic clay (Moculta quarry, Australia). If you start seeing montgomeryite, jarosite, cacoxenite in float, you are in the right ground. Typical habit: foliated, reniform. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify calcioferrite?+
Where is calcioferrite found?+
What rocks look like calcioferrite?+
What minerals are found with calcioferrite?+
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What is calcioferrite used for?+
Find calcioferrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
