Pseudobrookite, Aranga, New Zealand

Mineral Matters #379

I have been going through a few micros from New Zealand in recent days, and came across this nice little pseudobrookite.

The name pseudobrookite comes from the Greek words ψευδής (meaning false) and brookite (another titanium dioxide). The name reflects the historical confusion between pseudobrookite and brookite due to their similar appearances.

Pseudobrookite is found in a few localities in New Zealand, but is uncommon at Aranga Quarry. It is most commonly found in rhyolite or similar rocks. It occurs as prismatic crystals that are either black or red/brown in colour. The red can be quite striking when light is shone through the crystal.

The Aranga Quarry is perhaps best known for its cavansite specimens found a few years ago. Only small, nothing like the Indian specimens, but cute all the same. Pentagonite has recently been confirmed too! It is also the Type Locality for the mineral waipouaite, another vanadium-bearing species.

Below: A red prismatic pseudobrookite embedded in chabazite-Ca, Aranga Quarry (Stone's Quarry; Hood Road Quarry), Aranga, Kaipara District, Northland Region, New Zealand. Width of view 3mm. Click on the image for a higher resolution version.