igneous

Chinese Writing Stone

Porphyritic Basalt or Porphyritic Andesite

Hardness: 5-6 (Mohs scale); Color: Dark green to black groundmass with cream to light green needle-like crystals; Luster: Dull to sub-vitreous; Crystal Structure: Porphyritic (fine-grained matrix with large inclusions); Cleavage: None (conchoidal fracture).

Hardness: 5-6 (Mohs scale)
Luster: Dull to sub-vitreous

Identified March 29, 2026More igneous →

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Physical properties

Formation & geological history

Formed from volcanic activity where magma cooled in two stages: first slowly deep underground to form large phenocrysts, then rapidly at or near the surface to form the fine-grained matrix. Often associated with the Permian period (250-300 million years ago).

Uses & applications

Primarily used for lapidary work including cabochons, beads, and decorative carvings. Highly valued by crystal collectors for aesthetic beauty and use in metaphysical practices.

Geological facts

The name comes from the distinct needle-like andalusite or feldspar crystals that resemble Chinese calligraphy characters. While often found in China, high-quality specimens are also frequently sourced from the foothills of the Sierra Nevada mountains in California.

Field identification & locations

Identify by looking for the contrast between a very dark basaltic background and lighter, geometric, elongated crystal clusters. It is commonly found in riverbeds or mountain ranges with high volcanic history. Collectors should look for distinct, sharp crystal 'strokes'.

Other igneous specimens

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

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Dark Igneous Rock (Likely Basalt or Diabase)

Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral