Azurite is a soft, deep-blue copper carbonate hydroxide mineral produced by weathering of copper ore deposits. It is not a common or abundant mineral but is well-known for its characteristic deep blue to violet-blue color. Azurite has a chemical composition of Cu3(CO3)2(OH)2. It has been used as an ore of copper, as a pigment, as a gemstone, and as an ornamental stone in many parts of the world for thousands of years.
Azurite usually forms when the copper from subsurface copper ores dissolves into carbon-dioxide-laden waters and transported to a new geochemical environment. The precipitation of Azurite occurs in pore spaces, fractures, and cavities of the subsurface rock. Another copper carbonate mineral, Malachite, forms under similar conditions and these two minerals are often intergrown with one another producing a material known as azurmalachite.
Azurite has diagnostic properties of deep blue color, softness, and exceptionally high specific gravity for a non-metallic mineral. It has light blue streak and produces effervescence with dilute hydrochloric acid.
Uses of Azurite
Although Azurite is rarely found in large deposits, it has many uses.
Physical Properties
Azurite usually forms when the copper from subsurface copper ores dissolves into carbon-dioxide-laden waters and transported to a new geochemical environment. The precipitation of Azurite occurs in pore spaces, fractures, and cavities of the subsurface rock. Another copper carbonate mineral, Malachite, forms under similar conditions and these two minerals are often intergrown with one another producing a material known as azurmalachite.
Azurite has diagnostic properties of deep blue color, softness, and exceptionally high specific gravity for a non-metallic mineral. It has light blue streak and produces effervescence with dilute hydrochloric acid.
Uses of Azurite
Although Azurite is rarely found in large deposits, it has many uses.
- Copper Prospecting - Azurite is an indicator mineral for subsurface copper deposits. The presence of abundant azurite indicates the presence of copper ore nearby.
- Mining - Azurite has been used as a copper ore for thousands of years. However, Azurite deposits are usually not large enough to mine thesedays. They can be mined along with other ores in existing copper mines.
- Jewelry - Azurites are soft, so they can be easily cut and shaped into ornaments. However, its soft and brittle nature is a matter of concern as it lacks durability. The heat or air circulation can slowly weather the mineral into Malachite.
- Pigments - Azurite has been used as a pigment since ancient times. It is used as a pigment in blue paint mainly by painters who prefer historical methods. However, Azurite slowly weathers into Malachite and the blue pigments turns into green over time. So, it's not commonly used as there are synthetic paints with uniform color are available.
- Mineral Collecting - The mineral collectors appreaciate deep blue color, nodular habit, and crystalline structure of Azurite. The alteration is a problem for collectors as it causes dull and greenish appearance.
Physical Properties
| Property | Value |
|---|---|
| Category | Carbonates |
| Crystal System | Monoclinic |
| Color | Deep blue to violet blue |
| Streak | Light blue |
| Luster | Vitreous, earthy |
| Cleavage | Two distinct directions - perfect and poor |
| Mohs Scale Hardness | 3.5 to 4 |
| Diaphaneity | Opaque, translucent, transparent |
| Specific Gravity | 3.7 to 3.9 |
| Chemical Composition | Cu3(CO3)2(OH)2 |
| Diagnostic Properties | Deep blue color, high specific gravity, low hardness, effervescence in dilute HCl. |