Chabazite belongs to the large group of zeolites, minerals composed of hydrated aluminium silicates of calcium, sodium or potassium. Its generalized chemical formula is (Ca, Na2, K2, Mg)Al2Si4O12繚6H2O, but a number of varieties exist, depending on the relative prominence of one cation or the other. Chabazite belongs to the triclinic crystal system with twinned rhombohedral shapes being the common habitat. Colours range from white to yellow-orange and light green. Chabazites are most often found in voids and cavities in plutonic or extrusive (volcanic) rocks. This specimen is from Two Islands, N Scotia, and actual width 130 mm.