igneous
Porfido (Porphyritic Rock)
Porphyry (often Rhyolitic or Andesitic)
Hardness: 6-7 on Mohs scale; Color: Reddish-brown or purple groundmass with white or cream inclusions; Luster: Dull to sub-vitreous (when polished); Texture: Porphyritic (fine-grained matrix with larger visible crystals); Specific Gravity: 2.6-2.8.
- Hardness
- 6-7 on Mohs scale
- Luster
- Dull to sub-vitreous (when polished)
Identified More igneous →
Explore Porfido (Porphyritic Rock) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 on Mohs scale; Color: Reddish-brown or purple groundmass with white or cream inclusions; Luster: Dull to sub-vitreous (when polished); Texture: Porphyritic (fine-grained matrix with larger visible crystals); Specific Gravity: 2.6-2.8.
Formation & geological history
Formed from volcanic activity when magma experiences two stages of cooling: a slow stage underground creating large crystals (phenocrysts), followed by rapid cooling upon eruption or shallow intrusion forming the fine-grained matrix.
Uses & applications
Used widely in decorative landscaping, street paving (cobblestones), interior floor tiles, wall cladding, and as an ornamental stone in jewelry or tumbled stone collections.
Geological facts
The word Porphyry comes from the Greek word for 'purple.' Imperial Porphyry from Egypt was once more valuable than gold and was used exclusively for Roman emperors' thrones, statues, and sarcophagi due to its royal color.
Field identification & locations
Identified by the distinct contrast between the fine-grained base and the 'speckled' larger crystals. Commonly found in regions with volcanic history like Italy, Egypt, Mexico, and the Southwestern US. Collectors look for high contrast and color saturation.
