Ferraioloite is a rare phosphate mineral discovered in the Mangualde pegmatite of Portugal. Collectors should look for its distinctive yellow, transparent platy crystals, which often form in radial clusters within cavities of weathered phosphate zones.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrarenull family

Ferraioloite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this ferraioloite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch ferraioloite with a known reference. Ferraioloite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Ferraioloite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Ferraioloite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-orange.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, radial aggregates.

Often confused with

Ferraioloite vs. its common look-alikes — and how to tell them apart in the field.

Often found alongside ferraioloite

Minerals reported to co-occur with ferraioloite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Mg(Fe³⁺)₄(PO₄)₄(OH)₂·8H₂O
Mohs hardness: 2-3
Density: 2.81 g/cm³
Colors: Yellow Yellow-orange
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Platy Crystals, Radial Aggregates
Cleavage: Perfect in One Direction
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find ferraioloite

Classic worldwide localities

Mangualde pegmatite, Portugal

Field-hunting tip

Look in granite pegmatites country — that is the host setting where ferraioloite typically forms. If you start seeing triphylite, fairfieldite, luecite in float, you are in the right ground. Field specimens usually show a platy crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ferraioloite?+

Mohs hardness is 2-3. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellow-orange.

Where is ferraioloite found?+

Notable localities include Mangualde pegmatite, Portugal.

How much is ferraioloite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like ferraioloite?+

Ferraioloite is most often confused with Phosphosiderite, Strengite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ferraioloite?+

Ferraioloite commonly co-occurs with Triphylite, Fairfieldite, Luecite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ferraioloite form in?+

Ferraioloite typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ferraioloite used for?+

Ferraioloite is used in collector.

Find ferraioloite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.