In China, many billiard table vendors are unaware of the differences between billiard table slates, resulting in various names appearing on the market, such as marble, volcanic rock, bluestone, inkstone, and black inkstone.
First, volcanic rock is unsuitable for billiard tables. Volcanic rock is formed from magma deep within the Earth's crust or upper mantle, which cools and solidifies after intruding into the upper crust or erupting to the surface. This type of rock is porous and lightweight, similar to dried coal ash, brittle, and highly absorbent. Volcanic rock typically weighs only about one-quarter of granite or marble. Its cut and polished surface has many honeycomb-like pores, making it unsuitable for billiard tables.
Next is bluestone. In China, many people collectively refer to different types of bluestone, such as blue slate, blue sandstone, and blue limestone, as bluestone. However, these stones differ significantly in their physical properties and chemical composition. Globally, only one type of slate is officially recognized by billiard organizations: blue slate, known in English as SLATE. In the Chinese market, it's commonly known as bluestone, and some people also call it inkstone.
Currently, the world's three major billiard slate producing regions are Jiangxi, China; Genoa, Italy; and Minas Gerais, Brazil. Slates from these three locations are recognized by the World Billiards Organization and used in international tournaments.
