Microscope slides of orthoclase feldspar from Norway, these slides display the crystal structure of the mineral on a microscopic level which assists in the identification of this mineral in other slides. Orthoclase feldspar is a well known mineral and a common constituent found in many igneous rocks. It has two cleavage planes, which are at right angles to one another, resulting in the crystals breaking into rhombic forms and is the reason for its naming, being derived form the ancient Greek wording for "straight fracture." It is often pink in colour but can be white or pale grey. It is fairly hard at 6 - 6.5 on the Moh's scale of hardness and has a vitreous lustre, which means it shines or reflects light. Orthoclase is commonly found in many granitic rocks, being one of the main constituent minerals, the other two being quartz and mica. Each section is made to 30 microns thickness and the glass is 46 x 27 mm in size, supplied in a protective card sleeve with a label, ideal for microscopy & educational use.