All our rocks are carefully selected for educational study. They come in labelled trays. The trays are normally 3″ x 2″ size depending on the rarity of the specimen. Average specimen size is shown below. These are ideal for classroom teaching and are a size that can be easily passed round the classroom for students to get a feel for each type.
Biotite granite is a coarse grained, felsic intrusive rock, the minerals which make up a granite are typically quartz, feldspars and micas. In the case of biotite granite, the constituent minerals are milky (white) quartz, plagioclase feldspar which is often white and biotite mica crystals.