Ink stone

An inkstone (simplified Chinese: 砚; traditional Chinese: 硯; pinyin:  yàn) (simplified Chinese: 砚台; traditional Chinese: 硯臺; pinyin: yàn tái) (Japanese: 硯 suzuri) (Korean: 벼루 byoru) is a stone mortar for the grinding and containment of ink.

In addition to stone, inkstones are also manufactured from clay, bronze, iron, and porcelain. The device evolved from a rubbing tool used for rubbing dyes dating around 6000 to 7000 years ago.

Traditional East Asian ink is solidified into inksticks. Usually, some water is applied onto the inkstone (by means of a dropper to control the amount of water) before the bottom end of the inkstick is placed on the grinding surface and then gradually ground to produce the ink. More water is gradually added during the grinding process to increase the amount of ink produced, the excess flowing down into the reservoir of the inkstone where it will not evaporate as quickly as on the flat grinding surface, until enough ink has been produced for the purpose in question. The Chinese grind their ink in a circular motion with the end flat on the surface whilst the Japanese push one edge of the end of the inkstick back and forth.

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Wikipedia