Where is Granite with Copper Staining found?
Granite (igneous rock) with secondary copper minerals (e.g., malachite or chrysocolla)
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Open the appGranite with Copper Staining occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Granite with Copper Staining
Southwestern United States (Arizona, New Mexico)
Known for numerous porphyry copper deposits where granite and granodiorite intrusions are extensively altered and mineralized, leading to widespread copper staining in surrounding rocks.
Andes Mountains (Chile, Peru)
Major copper mining regions with extensive granitic batholiths and associated hydrothermal alteration, often exhibiting copper staining.
Cornwall, England
Historically significant tin and copper mining district where granitic intrusions are common and show evidence of copper mineralization and staining.
Ural Mountains, Russia
Contains numerous copper deposits associated with granitic and other intrusive rocks, where secondary copper minerals are prevalent.
Collecting tips
- Look for Green and Blue Hues. The most obvious indicator is the presence of green (malachite, chrysocolla) or blue (azurite) stains or coatings on the granite surface, especially in fractures or weathered areas.
- Examine Weathered Outcrops. Secondary copper minerals are often more visible on weathered surfaces where primary sulfides have oxidized.
- Check Near Known Copper Deposits. Areas with historical or active copper mining operations are prime locations to find granite with copper staining, as it indicates the presence of copper mineralization.
- Acid Test (Caution Advised). A small drop of dilute hydrochloric acid (HCl) will cause malachite and azurite to effervesce (fizz) due to their carbonate content. Chrysocolla will not effervesce. Always use caution and appropriate safety gear when handling acids.
Quick Check
- Color:
- Granite: White, gray, pink, red with black specks. Staining: Green (malachite, chrysocolla) or blue (azurite).
- Luster:
- Granite: Vitreous to pearly. Staining: Dull, earthy, silky, or vitreous.
- Streak:
- Granite: White (quartz, feldspar), gray (biotite). Malachite: Light green. Azurite: Light blue. Chrysocolla: White.
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