metamorphic (man-made)

Porcelain (Stoneware Ceramic)

Mullite / Silica-glass composite (Al6Si2O13)

Hardness: 6-7 (Mohs scale), Color: White to off-white, Luster: Vitreous/Glossy (glazed), Crystal Structure: Microcrystalline mullite in an amorphous glass matrix, Specific Gravity: 2.3–2.5

Identified March 22, 2026More metamorphic (man-made) →

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Physical properties

Hardness: 6-7 (Mohs scale), Color: White to off-white, Luster: Vitreous/Glossy (glazed), Crystal Structure: Microcrystalline mullite in an amorphous glass matrix, Specific Gravity: 2.3–2.5

Formation & geological history

Formed by high-temperature firing (metamorphism) of kaolin (clay), feldspar, and quartz at temperatures between 1,200 and 1,400 °C. Historically originated in China during the Tang Dynasty.

Uses & applications

Used in the manufacturing of dinnerware (cups, plates), electrical insulators, sanitary ware, dental crowns, and laboratory equipment due to low permeability and high thermal shock resistance.

Geological facts

Commonly known as 'China' because for centuries, the secret of its production was known only to Chinese potters. It is translucent when thin and produces a distinct ringing tone when struck.

Field identification & locations

Identified in the field by its white fracture surface, translucency, and ceramic 'clink'. Widely found in residential and commercial settings globally. Collectors look for specific backstamps or maker marks for provenance.

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Fired Clay Brick (Anthropic Rock substitute)

Anthropogenic polycrystalline ceramic (predominantly Mullite and Quartz: Al6Si2O13 + SiO2)

metamorphic (man-made / anthropic)

Clay Brick

Ceramic structural unit (Al2O3·2SiO2·2H2O as precursor)

metamorphic (man-made/anthropogenic)

Porcelain (Kaolin-based)

Alumina silicate ceramic (composed primarily of Kaolinite: Al2Si2O5(OH)4)

metamorphic (man-made/engineered)

N/A - Non-Geological Item

not a rock/mineral

Unidentifiable Rock Fragment

Uncertain

Porcelain (White Ceramic)

Mullite-bearing Vitrified Ceramic (Major phases: Mullite Al6Si2O13, Glassy Silica SiO2)

metamorphic