Purple Clay Lidden Cup

盖杯 (pinyin: gàibēi; literally, "lidden cup“)  is a Chinese covered bowl used for the infusion and consumption of tea, first created during the Ming Dynasty.

Yixing clay (simplified Chinese: 宜兴; traditional Chinese: 宜興; pinyin: Yíxīng; Wade–Giles: I-Hsing) is a type of clay from the region near the city of Yixingin Jiangsu province, China. Its use dates back to the Song Dynasty (960 - 1279) when sandy clay was first mined around Lake Taihu in China. From the 17th century on, the ware was commonly exported to Europe. The finished stoneware, which is used for teaware and other small items, are usually red or brown in color. They are known as Purple Sand ware, and are typically unglazed. 

Purple clay is a kind of natural mineral clay. A purple clay teapot has a duplex air vent structure, so it is well ventilated and good at heat preservation and transmission. When quality tea meets a nice teapot, it will release its taste and aroma thoroughly.

 *Information from Purple Cane, Wikipedia.