igneous
Porphyry (Flower Stone)
Porphyritic Basalt or Andesite
Mohs hardness 6-7, dark grey to black groundmass with distinct pink, white, or yellow mineral inclusions (phenocrysts). Dull to vitreous luster, fine-grained matrix with large visible crystals.
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Physical properties
Mohs hardness 6-7, dark grey to black groundmass with distinct pink, white, or yellow mineral inclusions (phenocrysts). Dull to vitreous luster, fine-grained matrix with large visible crystals.
Formation & geological history
Formed via two-stage cooling of magma: slow cooling deep underground creates large phenocrysts (often feldspar), followed by rapid cooling during eruption to form the fine-grained matrix.
Uses & applications
Decorative stones, landscaping, construction aggregate, and jewelry/ornamental carving depending on the beauty of the inclusions.
Geological facts
The term porphyry comes from the Greek word for purple, as the Romans prized a specific purple porphyry for imperial statues. This specimen shows a common variant often called flower stone or peanut wood (if silicified).
Field identification & locations
Identified by the distinct contrast between the dark host rock and the lighter, crystal-shaped spots. Commonly found in volcanic belts, glacial tills, or river beds in the Pacific Northwest and Japan.
