Taohe Ink Slab

Taohe stone is produced from the deep water of the Taohe River in Lintan County, Gansu Province, so it was given the name Taohe ink slab. This stone is green and thus is also known as ‘Taohe green stone’. It is a shallow metamorphosed argillaceous rock that is mainly composed of layered silicate minerals such as sericite and chlorite. It has a scale-like structure with a directional arrangement. It has the characteristics of the aluminium-rich series and illite clay, and it has low trace element and radioactive element contents. It has a density of 2.75–2.77 g/cm³, a saturated water absorption coefficient of 0.45–0.47, a porosity of 1.2–1.3% and a particle size of 0.011–0.053 mm. There are four main varieties: (1) duck head green, or ‘green ripple stone’, which is bluish green, has a ripple pattern, hard fine texture, jade-like lustre, and is a top-grade Taohe inkstone; (2) parrot green, which is dark green with a fine moist texture; those with dark ‘ink dots’ are most valuable; (3)...