Alleghanyite is a rare manganese silicate mineral typically found in metamorphosed ore deposits. It is most frequently encountered in massive or granular forms, often associated with other manganese minerals like spessartine and willemite.

Hardness

5.5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareHumite Group family

Alleghanyite

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

Is this alleghanyite?

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 alleghanyite with a known reference. Alleghanyite 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. Alleghanyite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Alleghanyite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: brownish red, reddish brown, orange brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: granular, massive, rarely as small tabular crystals.

Often confused with

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

mineral

Gahnite

Mohs 7.5-8

How to tell apart: Gahnite is the harder of the two (Mohs 7.5-8 vs. 5.5-6); streak differs — Alleghanyite leaves white, Gahnite leaves gray.

Often found alongside alleghanyite

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

All properties

Chemical formula: Mn₅(SiO₄)₂(OH)₂
Mohs hardness: 5.5-6
Density: 3.9 g/cm³
Colors: Brownish Red Reddish Brown Orange Brown
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Granular, Massive, Rarely as Small Tabular Crystals
Cleavage: Poor
Rarity: Rare
Uses: Collector, Research
Host rock: Metamorphosed Manganese Ore Deposits
Typical price: $20-100 for small thumbnail specimens

Where rockhounds find alleghanyite

Classic worldwide localities

Alleghany, North Carolina, USA
Franklin, New Jersey, USA
Langban, Sweden
Jakobsberg, Sweden

Field-hunting tip

Look in metamorphosed manganese ore deposits country — that is the host setting where alleghanyite typically forms. If you start seeing spessartine, willemite, franklinite in float, you are in the right ground. Field specimens usually show a granular, massive, rarely as small tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify alleghanyite?+

Mohs hardness is 5.5-6. It typically shows a vitreous luster. The streak is white. Common colors include brownish red, reddish brown, orange brown.

Where is alleghanyite found?+

Notable localities include Alleghany, North Carolina, USA; Franklin, New Jersey, USA; Langban, Sweden; Jakobsberg, Sweden.

How much is alleghanyite worth?+

Typical asking prices fall in the range of $20-100 for small thumbnail specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like alleghanyite?+

Alleghanyite is most often confused with Gahnite, Spessartine, Rhodonite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with alleghanyite?+

Alleghanyite commonly co-occurs with Spessartine, Willemite, Franklinite, Pyroxmangite, Jacobsite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does alleghanyite form in?+

Alleghanyite typically forms in metamorphosed manganese ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is alleghanyite used for?+

Alleghanyite is used in collector, research.

Find alleghanyite on the map

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