igneous

Chinese Writing Stone

Porphyritic Basalt (or Andesite) with Feldspar inclusions

Hardness: 5-6 (Mohs); Color: Dark green/black matrix with white or cream inclusions; Luster: Dull to sub-vitreous; Structure: Porphyritic (fine-grained matrix with large crystals); Cleavage: None (rock mass); Specific Gravity: 2.7-3.0

Hardness: 5-6 (Mohs)
Color: Dark green/black matrix with white or cream inclusions
Luster: Dull to sub-vitreous

Identified February 27, 2026More igneous →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through two-stage cooling of volcanic magma. Large plagioclase feldspar crystals (phenocrysts) formed slowly underground (Proterozoic to Mesozoic eras), followed by rapid surface cooling of the surrounding basaltic matrix during eruption.

Uses & applications

Primarily used for lapidary work including cabochons, carvings, and decorative tiles. It is popular in metaphysical circles and for ornamental jewelry.

Geological facts

Also known as 'Porphyry', it gets its name because the white crystals resemble Chinese characters or calligraphy marks. It is often confused with Snowflake Obsidian, but it is much harder and more durable.

Field identification & locations

Identify by looking for white, elongated lath-like crystals set against a dark, dense, fine-grained background. Found largely in the Yangtze River region of China and the foothills of the Sierra Nevada mountains in California. Collectors should look for high contrast between the 'ink' and the 'paper'.

Other igneous specimens

See all

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

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

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Blue Apatite

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

mineral

Magnetite

Magnetite (Fe3O4)

mineral