igneous
Weathered volcanic rock, likely altered basalt/andesite
Fine-grained mafic to intermediate volcanic rock; possible chlorite–calcite alteration
AI-generated identification · may be incorrectGray-brown, strongly weathered and porous-looking, with a dull earthy luster and an apparent greenish alteration patch. Likely hardness about 5–6, but softness may result from weathering; crystal grains are too fine to resolve, and no clear cleavage is visible.
Identified More igneous →
Explore Weathered volcanic rock, likely altered basalt/andesite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Gray-brown, strongly weathered and porous-looking, with a dull earthy luster and an apparent greenish alteration patch. Likely hardness about 5–6, but softness may result from weathering; crystal grains are too fine to resolve, and no clear cleavage is visible.
Formation & geological history
Probably lava or volcanic fragment later altered by groundwater, producing green chlorite-like minerals and possibly calcite. Volcanic rocks are common in the Philippines, including near Bohol, though the exact age cannot be determined from this photograph.
Uses & applications
Unweathered basalt and andesite are used as aggregate, road stone, and building material; this small weathered specimen has mainly educational or collector value.
Geological facts
The green area may be chlorite, epidote, or copper-bearing staining, but color alone cannot establish mineral identity. The smaller piece appears to be a similar weathered fragment.
Field identification & locations
Look for a fine-grained volcanic texture, irregular fracture, and lack of visible sedimentary layering. A fresh broken surface, streak test, hardness test, dilute acid test, and hand-lens inspection would distinguish basalt/andesite from altered limestone or concretion; the image is not diagnostic.
