Azurite is a deep blue mineral with an opaque vitreous luster. Knowing the periodic table, it would be classified under copper oxide – particularly copper (II) carbonate hydroxide chloride. This particular mineral occurs as small crystals that might be cut into a rough octahedron, an equilateral triangle with three scalene triangles on its two opposing faces. It has been found in many places worldwide, though the most important deposits are in PE and Siberia.
Azurite is not just something to look at; it is a very interesting mineral concerning its chemical properties. First, it is the most durable copper carbonate hydroxide compound – without a doubt. Second, it is one of the most poorly ordered (structure) minerals known to man – with a radius of 0.17 Å. That is to say; azurite has a high degree of disorder. Third and finally, it is also very interesting chemically.
Benefits of Azurite
Although azurite is the most durable of all known minerals, it is not a very useful compound because it has only one stable structural form – a low-density octahedron. Therefore, it cannot be used as an ore of any more useful mineral, such as goethite. Here are some of its benefits:
1. Azurite has great chemical stability.
It has been found that other compounds of azurite are more stable than PbS and CdS, for example, at room temperature and after prolonged exposure to light.
2. Azurite is one of the most insoluble minerals known.
It has a hardness value of 7 on the Mohs scale and is also impermeable to gases at room temperature. That means it will sink in water but not dissolve in it at all despite its weak structure. However, the natural form of azurite, the octahedron, is so poorly ordered that it dries out quickly and fragments into small pieces that are not soluble in water.
3. The near-perfect octahedral crystal shape is very interesting to look at.
Because the chemical composition of this mineral is so pure, there are no impurities inside it. It consists of only single atoms of copper and oxygen. If you were to make a ball out of azurite and throw it into the wind, it would be completely round and have the same weight as a real ball.
4. Its hardness makes it resistant to scratches (have you ever seen goethite gets scratched?).
Azurite has a Mohs value of 7, so it is harder and less brittle than glass. It would probably be as fragile as goethite if it were not for its hardness. Azurite has a fairly high toughness for a mineral. It takes about 20 times more pressure to fracture azurite (5 GPa) than to break it apart (0.5 GPa).
5. Its density is very low so that light objects can be made from it.
As mentioned above, azurite has a 2.9 g/cm density, which is lower than glass (about 2.5) and goethite (about 4). This means that a car could be made lighter if its frame were made of azurite because of the relative lack of mass.
6. Its rarity and low density make it a great gemstone.
Because of its color, high transparency and hardness, it is also often used to make jewelry. It can be cut into almost any shape people want so that it can be polished beautifully and made into any form they wish. However, because azurite has such a high hardness, this could get rather complicated to cut.
What makes Azurite Special?
What makes azurite special is its purplish-blue color and the fact that it occurs in a wide variety of crystal shapes – including the perfect octahedron, which is rare and beautiful. Some other minerals come in various colors – gold, silver, red, etc., but azurite is unique in that it will never occur in another color.
Azurite is a very interesting mineral because of its brilliant chemical and physical properties. Its durability, non-toxicity and chemical inertness make it a great compound, but its color and crystal shape are what make the azurite itself a work of art. Azurite is the only mineral that takes this form and not another – so it has no other color than blue (besides an over-abundance of iron). It is also one of the most insoluble compounds in nature, making it great for jewelry.