Loseyite is a very rare carbonate mineral almost exclusively found in the Franklin mining district of New Jersey. It is characterized by its delicate, bladed white to light blue crystals that often form radiating clusters on a matrix of other zinc-rich minerals.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Loseyite

Hardness: ~3
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this loseyite?

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 loseyite with a known reference. Loseyite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: bluish white, brownish, brownish white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: bladed crystals, radial aggregates.

Often confused with

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

mineral

Hodgkinsonite

Mohs <5

How to tell apart: Hodgkinsonite is the harder of the two (Mohs <5 vs. ~3).

How to tell apart: Luster reads vitreous on Loseyite and silky, dull, earthy on Sussexite.

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Often found alongside loseyite

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

All properties

Chemical formula: (Mn,Zn)₇(CO₃)₂(OH)₁₀
Mohs hardness: ~3
Density: 3.27 g/cm³
Colors: Bluish white Brownish Brownish white
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Bladed crystals, radial aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: A very rare mineral occurring in veinlets in massive ore in a metamorphosed stratiform zinc orebody

Where rockhounds find loseyite

Classic worldwide localities

Franklin, Sussex Co., New Jersey, USA

Field-hunting tip

Where it forms: A very rare mineral occurring in veinlets in massive ore in a metamorphosed stratiform zinc orebody. If you start seeing pyrochroite, sussexite, chlorophoenicite in float, you are in the right ground. Typical habit: bladed crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify loseyite?+

Mohs hardness is ~3. Luster: vitreous. The streak is white. Common colors include bluish white, brownish, brownish white.

Where is loseyite found?+

Notable localities include Franklin, Sussex Co., New Jersey, USA.

What rocks look like loseyite?+

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

What minerals are found with loseyite?+

Loseyite commonly co-occurs with Pyrochroite, Sussexite, Chlorophoenicite, Calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does loseyite form in?+

Where it forms: A very rare mineral occurring in veinlets in massive ore in a metamorphosed stratiform zinc orebody. Working float back to the host body is the standard way to chase a fresh occurrence.

What is loseyite used for?+

Loseyite is used in collector.

Find loseyite on the map

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