Big feldspar gabbro thin section exhibiting feldspar crystals much larger than those present in the ordinary gabbro we supply. Besides the large feldspar, the composition is largely the same as ordinary gabbro and it too forms in plutonic environments however it cools at a slower rate. Pyroxenes ( generally clinopyroxene ), abundant plagioclase and minor amounts of olivine and amphibole comprise this rock. Characteristic simple twinning in the plagioclase and the bright colours of the pyroxene make for an attractive thin section, perfect for educational use. These samples of Big Feldspar gabbro come from Carrock Fell, Cumbria. The slides supplement the hand specimens nicely and are useful for interpreting the crystalisation history of the rock. Each section is made to 30 microns thickness and the glass is 46 x 27 mm in size with a cover slip. Supplied in a protective card sleeve with a label, ideal for microscopy.