igneous
Copper-bearing volcanic breccia
Altered andesite or rhyolite breccia with secondary copper minerals, likely chrysocolla and/or malachite
AI-generated identification · may be incorrectHardness is roughly 3–6, with earthy to dull luster, pale green, tan, cream, and brown colors, and a highly porous, irregular texture. Angular rock fragments appear cemented by silica- and carbonate-rich alteration; no clear crystal cleavage is visible.
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Physical properties
Hardness is roughly 3–6, with earthy to dull luster, pale green, tan, cream, and brown colors, and a highly porous, irregular texture. Angular rock fragments appear cemented by silica- and carbonate-rich alteration; no clear crystal cleavage is visible.
Formation & geological history
Likely formed when volcanic rock fragments were cemented and later altered by hydrothermal fluids, depositing green secondary copper minerals. The age depends on its locality, commonly ranging from Paleozoic to Cenozoic in copper districts.
Uses & applications
Primarily a collector specimen or lapidary rough; attractive pieces may be polished or cut. It has little conventional construction value unless abundant as local aggregate.
Geological facts
The green coloration is consistent with chrysocolla, malachite, or copper-bearing clay minerals, but image-based identification cannot distinguish them reliably. Blue-green copper staining commonly marks oxidized portions of copper deposits.
Field identification & locations
Look for angular clasts, porous altered matrix, and green-blue coatings or veins; a streak, hardness, acid, and copper-mineral tests are useful. Common in arid copper regions such as Arizona, Nevada, Chile, Mexico, and Australia.
