Pyrosmalite-(Fe) is a rare manganese-iron silicate typically found in skarn environments. Collectors prize it for its distinct, mica-like pearly luster on its perfect cleavage planes and its characteristic tabular hexagonal crystal habit.

Hardness

4.5

Mohs

Luster

Vitreous

Streak

Light green

Transparency

Semitransparent

mineralrarePyrosmalite Group family

Pyrosmalite-(Fe)

Hardness: 4.5
Luster: Vitreous
Streak: Light green
Transparency: Semitransparent

Is this pyrosmalite-(fe)?

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 pyrosmalite-(fe) with a known reference. Pyrosmalite-(Fe) sits at Mohs 4.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: light green.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: green blackish, pale liver brown, gray.
5
Look at form & habit
Crystal system: hexagonal. Typical habit: massive, prismatic.

Often confused with

Pyrosmalite-(Fe) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Biotite

Mohs 2.5-3

How to tell apart: Pyrosmalite-(Fe) is noticeably harder (Mohs 4.5 vs. 2.5-3); streak differs, so Pyrosmalite-(Fe) leaves light green, Biotite leaves white; luster reads vitreous on Pyrosmalite-(Fe) and splendent to submetallic, vitreous, pearly on cleavage on Biotite.

How to tell apart: Pyrosmalite-(Fe) is noticeably harder (Mohs 4.5 vs. 2-3); streak differs, so Pyrosmalite-(Fe) leaves light green, Phlogopite leaves white; luster reads vitreous on Pyrosmalite-(Fe) and pearly to submetallic on cleavage on Phlogopite.

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Often found alongside pyrosmalite-(fe)

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

All properties

Chemical formula: Fe₈Si₆O₁₅(OH)₁₀
Mohs hardness: 4.5
Density: 3.06-3.19 g/cm³
Colors: Green blackishPale liver brownGray
Streak: Light green
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Hexagonal
Crystal habit: Massive, prismatic
Cleavage: {0001}, good
Rarity: Rare
Uses: Collector
Host rock: Intergrown with sulfdes, formed during metamorphism of a stratiform Pb-Zn deposit; a retrograde reaction product derived from clinopyroxene in saline fluid inclusions in contact metamorphic rocks

Where rockhounds find pyrosmalite-(fe)

Classic worldwide localities

Pegmont lead-zinc deposit, 175 km southeast of Mt. Isa, Queensland, Australia
Sudbury, Ontario and the PGE-Au-As deposits of the Thomson nickel belt, Manitoba
Banská Štiavnica district, Slovakia

Field-hunting tip

Where it forms: Intergrown with sulfdes, formed during metamorphism of a stratiform Pb-Zn deposit; a retrograde reaction product derived from clinopyroxene in saline fluid inclusions in contact metamorphic rocks. If you start seeing fayalite, greenalite, galena in float, you are in the right ground. Typical habit: massive, prismatic. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify pyrosmalite-(fe)?+

Mohs hardness is 4.5. Luster: vitreous. The streak is light green. Common colors include green blackish, pale liver brown, gray.

Where is pyrosmalite-(fe) found?+

Notable localities include Pegmont lead-zinc deposit, 175 km southeast of Mt. Isa, Queensland, Australia; Sudbury, Ontario and the PGE-Au-As deposits of the Thomson nickel belt, Manitoba; Banská Štiavnica district, Slovakia.

Is pyrosmalite-(fe) safe to handle?+

Contains chlorine and potential manganese/iron dust inhalation hazards; handle with care and wash hands after contact.

What rocks look like pyrosmalite-(fe)?+

Pyrosmalite-(Fe) is most often confused with Biotite, Phlogopite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with pyrosmalite-(fe)?+

Pyrosmalite-(Fe) commonly co-occurs with Fayalite, Greenalite, Galena, Sphalerite, Clinopyroxene, Hornblende. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does pyrosmalite-(fe) form in?+

Where it forms: Intergrown with sulfdes, formed during metamorphism of a stratiform Pb-Zn deposit; a retrograde reaction product derived from clinopyroxene in saline fluid inclusions in contact metamorphic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is pyrosmalite-(fe) used for?+

Pyrosmalite-(Fe) is used in collector.

Find pyrosmalite-(fe) on the map

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