Malachite
Botryoidal Malachite
Although I love all vividly coloured minerals, I have always been fascinated with the green growth patterns of malachite. These growth patterns of various greens are due to the botryoidal habit that is most common in malachite. Although botryoidal translates to ‘bunch of grapes’, I think a lot of the raw botryoidal malachite pieces look more like velvety green cauliflower. What do you think?
Initial growth of Malachite
Malachite is a secondary mineral of copper. It occurs when carbonate-rich water is in contact with a copper deposit. In these areas, the copper & carbonate-rich water would flow through fractures and cavities in the surrounding rock. As it flows, green malachite, other hydrous copper carbonates (such as deep blue azurite) and hydrous copper silicates (such as turquoise chrysocolla) get precipitated in the openings. You can learn more about these other copper minerals in my future posts.
Where the copper & carbonate-rich water continuously flows over the previously precipitated malachite, additional layers are deposited forming the cauliflower head (or bunch of grapes, if you like). If the botryoidal malachite is forming on the roof of a large cavity, stalactites can form. I’d like to cover stalactites in a future post, so for now just think of them as icicles (they are generally formed the same way).
That’s the science in a nutshell! Now, how is malachite used?
In 4000 BC, malachite was reported to be the first mineral heated in fire to produce a metal (in this case copper). This led to the search for other metallic ores. However, the Egyptians soon discovered that malachite had more value as a pigment in cosmetics and wall paint.
Besides a prized specimen for rock collectors, the most common uses of malachite today are for jewelry (mainly beads and cabochons) and small sculptures (like my little box). The beautiful scalloped patterns in malachite, seen in cabochons and tumbled stones, are exposed when botryoidal malachite is polished.
Malachite box
Malachite - tumbled stone
Despite being one of the first indicators of a copper deposit, malachite (especially in usable quantities) is still a rare mineral. This makes genuine malachite quite expensive and provides a huge incentive to make imitations. My next post will help you differentiate between real and fake malachite, so you can make an informed choice on your next jewelry purchase.
