This week we look at another kind of Yixing clay, and a subtype of zini (purple clay), called original ore Qinghuini 原矿青灰泥.
Qinghuini is mined from a layer found between the layer of zini ore (purple clay when fired) and the layer of duanni ore (yellow clay when fired). When it is first taken out of the ground, qinghuini resembles a purple rock. The clay is processed in the same way as other original ore zisha (Yixing clay); it is crushed, sieved, mixed with water, aged, shaped, and fired in a kiln. After being fired at 1200C, the clay is a greyish dark purple with golden flecks or grains appearing over the surface. These golden grains are the duanni in the qinghuini clay.
Although qinghuini is a mixture of both duanni and zini, there is a higher percentage of zini in the ore and the processed clay behaves more like zini than duanni. It is very malleable, it has a similar shrinking rate to zini when fired (around 13%), similar porosity and permeability, and like zini it can be fired successfully at a wide range of temperatures. As a result, qinghuini has been classified as a subtype of zini rather than as a type of duanni.
Like other kinds of zini, qinghuini is a very versatile clay that works well with all kinds of tea. Its distinctive appearance and versatility have made qinghuini a popular clay with Chinese tea drinkers.