igneous

Porphyritic Basalt (Flowerstone)

Porphyritic Basalt (Mafic volcanic rock)

Hardness: 6.0-6.5 on the Mohs scale (matrix is harder, phenocrysts are softer feldspar). Color: Dark grey to greenish-black matrix with white, cream, or light pink 'flower-like' rectangular crystals. Luster: Dull to earthy matrix with vitreous (glassy) phenocrysts.…

Hardness: 6
Luster: Dull to earthy matrix with vitreous (glassy) phenocrysts

Identified March 20, 2026More igneous →

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Physical properties

Formation & geological history

Formed via two-stage cooling. Magma cooled slowly deep underground, allowing large plagioclase feldspar crystals (phenocrysts) to grow. The magma was then erupted quickly, causing the surrounding liquid to cool rapidly into a fine-grained dark matrix. These are common in volcanic regions like the Pacific Northwest (Triassic-Jurassic age).

Uses & applications

Primary use as a decorative lapidary stone. When cut and polished, the 'flower' patterns make attractive jewelry, cabochons, and paperweights. In industry, basalt is crushed for high-strength road base and aggregate.

Geological facts

Commonly referred to as 'Flowerstone' or 'Chinese Writing Stone' (though that is technically an andalusite porphyry), this rock is the official stone of Texada Island in British Columbia. It records a specific moment in volcanic history where cooling rates shifted dramatically.

Field identification & locations

Identify in the field by looking for distinct rectangular or star-shaped white crystals 'suspended' in a dark, uniform volcanic rock. It is frequently found on beaches or in glacial till in volcanic arcs like British Columbia, Washington, and Oregon. High iron and magnesium content make the matrix dense.

Other igneous specimens

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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