A rare mineral specimen of Malachite Pseudomorph after Azurite. You can see that the Malachite is not in one of its natural forms, but instead is more like Azurite. A pseudomorph is when one mineral is chemically replaced by another mineral without changing the external form of the original mineral. In this case the Malachite has replaced the original Azurite mineral. Bright flashes of green from chatoyancy striations of the Malachite. Azurite shows good forms of chisel top tabular prismatic crystals jutting out from the matrix. Very collectible piece, both for it is a pseudomorph and a rare mineral from a great location. An excellent gift or treat for the mineral collector and a must for the Collection. For enhanced display is mounted on perspex pad, ready to go straight into your cabinet.
A rare mineral specimen of Malachite Pseudomorph after Azurite. You can see that the Malachite is not in one of its natural forms, but instead is more like Azurite. A pseudomorph is when one mineral is chemically replaced by another mineral without changing the external form of the original mineral. In this case the Malachite has replaced the original Azurite mineral. Bright flashes of green from chatoyancy striations of the Malachite. Azurite shows good forms of chisel top tabular prismatic crystals jutting out from the matrix. Very collectible piece, both for it is a pseudomorph and a rare mineral from a great location. An excellent gift or treat for the mineral collector and a must for the Collection. For enhanced display is mounted on perspex pad, ready to go straight into your cabinet.
Malachite is a green, very common secondary copper mineral with a widely variable habit. Named in antiquity by Pliny the Elder 79 CE. As molochitus after the Greek ”mallows” in allusion to the green colour of the leaves. Known in the new spelling, malachites, at least by 1661. Malachite is a green and common secondary copper mineral with widely variable habit. Frequently found as a pseudomorph after Azurite crystals, which are generally more tabular in shape.
The colour is due to Copper which is a strong coloring agent. Copper chemically combines with the carbonate groups CO3 and hydroxyls OH. Used as a dye for paints and fabrics. Unfortunately its colour is too deep and larger crystals can appear black. Small crystals and crusts show the lighter azure colour well. Often Azurite forms with Malachite.
Malachite and Azurite are closely related. Not only do they frequently occur together (pictured above), they also have very similar formulae. Malachite can also replace azurite, making a pseudomorph. Compare their formulas:
Azurite’s formula: Cu3(CO3)2(OH)2
Malachite’s formula: Cu2(CO3)(OH)2
The charges on the copper ions are the same for both minerals at positive two. But what causes the color change from azurite to malachite if the charge on the copper remains the same. Notice the different amounts of CuCO3 in the two formulas. The azurite seems to have an extra CuCO3.
Since the Cu(OH)2 is more oxidized than the CuCO3, the malachite is therefore more oxidized than azurite. This means that malachite represents a later stage of oxidation and the increased oxidation is what causes the color change. Formula for conversion adds a water molecule to two Azurite molecules and omits a carbon dioxide molecule.
The oxidation is persistent and actually ongoing, although very slow. Azurite paints made centuries ago have undergone the transformation of beautiful blue skies now have a most unusual green hue! Thankfully for mineralogists and collectors, this transformation is one of the most aesthetically pleasing in the mineral kingdom. There really is no comparison to any other mineral to mineral transformation in terms of overall beauty.
It is also an unimportant ore of copper, although its significance has been more impressive in the past. Fine crystal clusters, nodular specimens, and interesting and beautiful combinations with malachite are important pieces in anyone’s mineral collection. The magnificent color of Azurite is worth mentioning again as it truly is a one-of-a-kind in the mineral world. Azurite is one of those classic minerals.
Azurite forms at a lower temperatures than Malachite, which often replaces it pseudomorphically through hydration. A secondary Copper mineral in Sulfide deposits associated with Carbonate rocks. Also found in Sandstones as an impregnation caused by carbonatic water coming into comtact with water rich in copper sulfates.
Properties
Transparency Transparent if in thin crystals, otherwise translucent to opaque. Crystal System Monoclinic; 2/m. Crystal Habits Crystals have irregular blades with wedge shaped terminations. Also, aggregate crusts and radiating, botryoidal, nodular and earthy masses. Cleavage is good in one direction and fair in another. Fracture is conchoidal and brittle. Hardness is 3.5-4. Specific Gravity is 3.7+ (heavier than average). Streak is blue.
Associated Minerals are numerous and include malachite limonite, calcite, cerussite, quartz. Also chalcopyrite, native copper, cuprite, chrysocolla, aurichalcite, shattuckite, liroconite, connellite and other oxidized copper minerals.
Notable Occurrences include numerous localities worldwide, but special localities produce some outstanding specimens especially from Lasal, Utah; Bisbee, Arizona and New Mexico, USA; Mexico; Tsumeb, Nambia; Shaba, Congo; Toussit, Morocco; Australia and in many locations in Europe. Best Field Indicators are color, softness, crystal habits and associations.
A rare mineral specimen of Malachite Pseudomorph after Azurite. You can see that the Malachite is not in one of its natural forms, but instead is more like Azurite. A pseudomorph is when one mineral is chemically replaced by another mineral without changing the external form of the original mineral. In this case the Malachite has replaced the original Azurite mineral. Bright flashes of green from chatoyancy striations of the Malachite. Azurite shows good forms of chisel top tabular prismatic crystals jutting out from the matrix. Very collectible piece, both for it is a pseudomorph and a rare mineral from a great location. An excellent gift or treat for the mineral collector and a must for the Collection. For enhanced display is mounted on perspex pad, ready to go straight into your cabinet.
