Millerite

A nickel sulfide that grows as brassy, hair-thin needles, often inside geodes.

Millerite specimen — Photo: James St. John, CC BY 2.0, via Wikimedia Commons

How to identify millerite

Brass-yellow hair-like needles in sprays.
Often inside quartz or calcite geodes.
Metallic luster.

Often confused with

Rutilated Quartz
Rutile needles are trapped inside quartz rather than free-standing.
Compare side by side

Where it's found

Keokuk geodes, Iowa
Halls Gap, Kentucky
Wales

Uses

Collector specimens.

Rock tumbling

Not suitable for tumbling.

Did you know?

It's named after mineralogist William Hallowes Miller, who devised Miller indices for crystal faces.

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