Mineral description : Brookite

Brookite from Hardangervidda, Norway. Seven pale brownish crystals rests on a matrix of albite. The biggest crystal is about 5mm.

Mineral class	Oxides : Rutil Cassiterite group
Chemical formula	TiO2
Crystal system	Orthorombic
Habitus	Tabular to lamellar, rhombic or dipyramidic crystals.
Cleavage	Poor, fracture conchoidal, brittle.
Hardness	5.5 - 6
Density	4.1
Color	Brownish to black crystals to almost colorless.
Streak	Yellow to brownish.
Luster	Adamantine to sub metallic, transparent to opaque.
Description
Occurance
Associates	Quartz, adular, albite, anatase, titanite
Notes	Named after the Brittish crystallograph H. J. Brooke. Polymorph with rutile and Anatase. Does not melt, infusible. Unsolvable in acids.
Localities	Sweden : rare but a few localities exists. Alnön, Sundsvall, Medelpad. As small grains. (ref SGU Ba31, pg 267) Norway : Gamle grube, Strausheia. As a yellow mineral filling fractures in plagioclase. Gjerdingen, Nordmarka. In druses. Nedre Eiker. As pseudomorphs after titanite together with anatase. Matskorhae, Hardangervidda. As reddish brown thin crystals, up to 5mm, together with rutile and anatase. Hardangervidda. A number of localities are known in alpine veins. Often together with anatase, rutile and rock crystals. Vetllia, Böverdalen, Lom. A single crystal is known. Finland : It's been found but I don't know where. If you know, please send me a mail.

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