Snowflake Obsidian thin section microscope slides which exhibit radially clustered crystals of cristobalite within a glass matrix. Obsidian, also known as 'volcanic glass' is a felsic, extrusive igneous rock. Crystal growth is minimal / absent within obsidian due to rapid solidification rates which inhibit crystal growth thus giving the rock a glassy appearance. In the case of snowflake obsidian, over time, silica molecules within the glass rearrange into an organised crystal pattern i.e. crisobalite; this process is known as ' devitrification '. This material was collected in Anatolia, Turkey. Each section is made to 30 microns thickness. The glass is 46 x 27 mm in size, supplied in a protective card sleeve with a label, ideal for microscopy.