Polarized light micrograph of a thin section of agate microcrystals. Microscopic detail of banded agate. In the image we can see fibrous crystals of chalcedony, and microgranular quartz can be seen at the bottom. The agate is a semi-precious gemstone variety of chalcedony. It is a microcrystalline silica with a chemical composition of SiO2 (silicon dioxide), and some of its other physical properties are those of quartz. Its uses are: hardstone carving, decorative arts, jewellery, crafts and industry. Field of view size: 1.49 x 2.23 mm (0.059 x 0.088 in)