The Oil Spot Glaze was developed by the potters of Fujian Province in the Southern Song Dynasty CE 11125 - 1279. It is a decorating technique of black glazed stoneware bowls found in tombs and in the Jian ware kiln sites in Fujian Province in Southeast China. The Japanese named the black wares Temmoku, which were highly valued in the art of tea.
I am not a potter and have no experience with ceramic glazes, but I am inclined to think the tea dust glaze somehow was derived from the oil spot glaze. It is called tea dust because it resembles the type of tea leaves that were grounded into powder and made into a drink in the Song Dynasty, and the tradition continues on in Japan. My best guess is that this small bottle vase was an experimental piece, to test the composition of the tea dust glaze.
Dating: unsure
Dimensions: 2 inches high, 2 inches in diameter
Condition: good