Malachite is a natural mineral which has been known to man for thousands of years. It was first used as an ore of copper around 5000 BC and continued to be used extensively for this purpose throughout antiquity. It usually occurs close to the mineral azurite which although blue has an almost identical chemical composition to malachite. The reason why they're different colours is because the copper in malachite is more highly oxidized than it is in azurite hence over time and under the right conditions, one turns into the other.
Although malachite has always been popular as a gemstone, it is very soft and also porous hence must be handled with care. On Mohs scale of mineral hardness malachite grades 3½ to 4. To put that into perspective, diamond which is the hardest mineral scores 10 on Mohs scale. It's worth noting that malachite does have a tendency to mark if allowed to get wet and stones may also crack if exposed to sudden extreme temperature changes.