Cortlandite. Cortland, USA.

Thin Section Microscope Slide of rock from Stony Point Rockland, New York State, USA. This is part of an Ultramafic intrusion with some most unusual rock Types. This one contains olivine, rose pink highly pleochroic orthopyroxene, and dark brown pleochroic poikilitic kaersutite amphibole. (encloses other minerals). This makes it a cortlandite, a very rare rock indeed. The minerals are fresh and mostly unaltered.

 VERY rare and difficult to obtain, attractive, and very instructive. Limited material so this is expensive I'm afraid.

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Ultramafic Cumulate. Alaska.

This is a thin section of a ultramafic peridotite cumulate from the Brady Glacier Nunatak, La Perouse intrusion, Fairweather Range, S.E. Alaska USA. An exceptionally good cumulate texture, bright, colourless and totally fresh olivines in plagioclase and orthopyroxene poikilitic textured matrix. The orthopyroxene is in parts gradually altering to red/brown biotite, both parts in the same continuous crystal. Biotite is a hydrous mineral, so water must be present, but the olivine shows no sign of alteration. Highly Interesting.

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Actinolite in Talc. N.W. Scotland

This is a thin Section microscope slide of a rock from Auctertyre, near Kyle of Lochalsh, associated with the Lewisian (pre cambrian) 'inlier'. Well formed crystals of actinolite in a matrix of very fine grained talc. Very pretty in XPL.

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Ultramafic layered intrusion. Rum, Scotland

This is a thin section of  rock from the Isle of Rum, an island off the West coast of Scotland, South of Skye. This island is part of the Paleogene volcanic province active just before the opening of the Atlantic about 60 million years ago. The island was a volcano, and has been deeply eroded, more deeply than the other volcanoes in the province. The base of the magma chamber is exposed and a world famous series of layers, Peridotite and Troctolite, now make up the mountainous centre of the island.
This slide is from the famous ( among petrologists ) "Chromite Band" From the Eastern Layered Intrusion, one of the peridotite layers is separated by a band of chromite from the next troctolite layer. This slide shows both layers and the chromite. Illustrations of this are in most books about the Geology of Rum.
Only a few of these will be offered, I only have a very small amount of this material. Please enquire about availability before ordering. 

Limbergite. Limberg, Germany.

This is a thin section microscope slide of a very rare volcanic rock, Limbergite. From the carbonatite volcanic complex at Kaiserstuhl, in southern Germany. An interesting brown matrix contains titaniferous augite with the usual zoning and magnificent interference colours, olivine with altered rims and fresh centres, some crystals embayed. Outstanding amygdules, filled with zeolites, often different types, sometimes including an unidentified red one.

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Kentallenite. Lochaber, Scotland.

This is a thin section microscope slide of Kentallenite, a rare rock collected from the type location at Kentallen, on the shores of Loch Linnhe, in Scoland. Contains Olivine augite, biotite, and both plagioclase and orthoclase feldspar. Spectacular under crossed filters, the different minerals show up well and are easy to identify except the feldspars, which are a little more challenging. An unusual rock and difficult to classify, probably best called an olivine monzonite. See page 105 Atlas of Igneous rocks, MacKenzie et al. Highly recommended slide , to form part of any collection of Scottish rocks. The photos do not do it justice.

1 Slide