Anorthosite

A pale rock made almost entirely of plagioclase feldspar — it makes up the Moon's bright highlands.

Anorthosite specimen — Photo: Mike Davis, CC0, via Wikimedia Commons

How to identify anorthosite

Light gray to white, coarse feldspar.
Few dark minerals.
May flash blue like labradorite.

Often confused with

Marble
Marble fizzes and is much softer.
Compare side by side
Quartzite
Quartzite has no flat feldspar cleavage faces.
Compare side by side

Where it's found

Adirondack Mountains, New York
Nain, Labrador
Norway
The Moon

Uses

Dimension stone; source of labradorite.

Rock tumbling

Great for tumbling.

Did you know?

The Apollo 15 'Genesis Rock' is a piece of lunar anorthosite.

Think you could spot it from a blurry close-up?

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