Ferrobustamite is a member of the wollastonite group characterized by its iron-rich composition. It typically occurs in skarn deposits formed through the contact metamorphism of impure limestones, often appearing as fibrous or granular masses that can be difficult to distinguish from common wollastonite without chemical testing.

Hardness

5.5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareWollastonite Group family

Ferrobustamite

Hardness: 5.5-6
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this ferrobustamite?

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 ferrobustamite with a known reference. Ferrobustamite sits at Mohs 5.5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Ferrobustamite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Ferrobustamite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, yellowish, brownish, colorless.
5
Look at form & habit
Crystal system: triclinic. Typical habit: fibrous, massive, or as tabular crystals.

Often confused with

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

How to tell apart: Luster reads vitreous on Ferrobustamite and vitreous to silky on Pectolite.

Often found alongside ferrobustamite

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

All properties

Chemical formula: CaFeSi₂O₆
Mohs hardness: 5.5-6
Density: 3.5-3.6 g/cm³
Colors: White Yellowish Brownish Colorless
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Fibrous, Massive, Or as Tabular Crystals
Cleavage: Perfect in Two Directions
Rarity: Rare
Uses: Collector
Host rock: Metamorphosed Limestone or Skarn Deposits
Typical price: $20-100 per specimen depending on size

Where rockhounds find ferrobustamite

Classic worldwide localities

Broken Hill, Australia
Franklin, New Jersey, USA
Kalkar Quarry, California, USA
Vesuvius, Italy

Field-hunting tip

Look in metamorphosed limestone or skarn deposits country — that is the host setting where ferrobustamite typically forms. If you start seeing calcite, andradite, diopside in float, you are in the right ground. Field specimens usually show a fibrous, massive, or as tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ferrobustamite?+

Mohs hardness is 5.5-6. It typically shows a vitreous luster. The streak is white. Common colors include white, yellowish, brownish, colorless.

Where is ferrobustamite found?+

Notable localities include Broken Hill, Australia; Franklin, New Jersey, USA; Kalkar Quarry, California, USA; Vesuvius, Italy.

How much is ferrobustamite worth?+

Typical asking prices fall in the range of $20-100 per specimen depending on size. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like ferrobustamite?+

Ferrobustamite is most often confused with Wollastonite, Pectolite, Pyroxferroite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ferrobustamite?+

Ferrobustamite commonly co-occurs with Calcite, Andradite, Diopside, Wollastonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ferrobustamite form in?+

Ferrobustamite typically forms in metamorphosed limestone or skarn deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ferrobustamite used for?+

Ferrobustamite is used in collector.

Find ferrobustamite on the map

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