Spurrite is a white, yellow or light blue mineral with monoclinic crystals. Its chemical formula 4)2C
Spurrite is generally formed in contact metamorphism zones as mafic magmas are intruded into carbonate rocks Spurrite's space group is P 2/a. It is biaxial with a birefringence of 0.0390–0.0400, giving second order red interference colors when viewed under crossed polarizers in a petrographic microscope
The calcium , the silicon is in a four-fold coordination with the oxygen and the carbon is in two-fold coordination. One unique characteristic of spurrite is that it actually abides by two twin laws. Polysynthetic twinning can occur along its (001) and another type of twinning can occur parallel to its optical axes.