igneous
Andesite River Stones
Andesite
Hardness: 6-7 on Mohs scale; Color: Grey to grayish-green with salt-and-pepper texture; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic to porphyritic; Specific gravity: 2.4 - 2.8.
- Hardness
- 6-7 on Mohs scale
- Color
- Grey to grayish-green with salt-and-pepper texture
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Grey to grayish-green with salt-and-pepper texture; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic to porphyritic; Specific gravity: 2.4 - 2.8.
Formation & geological history
Formed from the cooling of intermediate volcanic lava. These specific specimens are water-worn, indicating they were shaped by fluvial (river) erosion over thousands of years.
Uses & applications
Used in landscaping, construction aggregate, road base, and occasionally as decorative stones for gardens or aquariums.
Geological facts
Andesite is the second most common volcanic rock after basalt. It is named after the Andes Mountains, where it is found in abundance at subduction zones.
Field identification & locations
Identify by its intermediate grey-green color and fine-grained texture. Found globally in volcanic arcs and riverbeds near mountainous terrain.
