igneous
Porphyritic Basalt (Flower Stone)
Basalt with Feldspar phenocrysts
Hardness: 6.0; Color: Dark grey to black groundmass with light yellowish-green crystals; Luster: Dull to sub-vitreous; Structure: Aphanitic with porphyritic texture; Cleavage: None; Specific Gravity: 2.8-3.0
- Hardness
- 6
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6.0; Color: Dark grey to black groundmass with light yellowish-green crystals; Luster: Dull to sub-vitreous; Structure: Aphanitic with porphyritic texture; Cleavage: None; Specific Gravity: 2.8-3.0
Formation & geological history
Formed from rapid cooling of volcanic lava on the Earth's surface. The larger crystals (phenocrysts) formed slowly at depth before the final eruption. Common in volcanic regions and riverbeds.
Uses & applications
Used as decorative garden stones, in aquarium landscaping, and as worry stones or talismans in some cultures. Polished specimens are used in jewelry.
Geological facts
Often called 'Flower Stone' or 'Chrysanthemum Stone' (though different from the limestone version) because the mineral inclusions resemble flower petals. This specific pebble has been smoothed by river or beach erosion.
Field identification & locations
Identified by a dark, dense matrix containing distinctly larger, lighter-colored mineral crystals. Commonly found on volcanic islands and coastal areas like the Pacific Northwest or Japan.
