Spending time at Natural History Museums is a bit like meditation for me, and I keep coming back to the same ones because I always see and learn something new every time. Here are a few among many pieces of art made by Mother Nature 🦕🌍🗿. 💎Figure 1: -Sparkling Amethyst crystals that are part of one of the largest known Amethyst geodes in the world. The geode in total represents a giant bubble within a layer of rock. Amethysts are a type of quartz that is basically silica, and they form as a secondary mineral close to or at Earth's surface. So in a way, their purpose is to fill in bubbles, cracks and cavities in old rocks to make everything into a solid piece as water with dissolved minerals deposits the material on the way while filtering through the bedrock ⛏. 💎Figure 2: The beautiful sisters, Azurite and Malachite. They are rich in copper and are basically the same mineral; only the difference is the charge of the copper ion in their formulas which results in different oxidation stages and thus different colours and crystal habits. Malachite, the green one, often results from weathering of copper ores, similar to copper coins or statues (like the Statue of Liberty) that turn green with oxidation. Azurite, the blue one, has been used as pigment dating back to ancient Egypt 🗽. 💎Figure 3: The classic duo of Aragonite and Calcite. The less fancy name for both of them is calcium carbonate, but the main difference between them is the different crystal systems they belong to. They are widely seen in coral reefs as "coral skeletons", and Aragonite provides the materials necessary for much sea life and keeps the ocean's pH close to its natural level. Calcium carbonate is also the primary material in shells. These minerals are very easy to dissolve, such as with hydrochloric acid, which results in bubbling on their surface as carbon dioxide is released in gas form. Sadly and similarly, this is now the fate of many coral reefs and marine lives with shells, with the acidity of the oceans increasing drastically. With Calcite and Aragonite fading away from our oceans, marine life will follow with a severe chain reaction 🐚. @amnh ©Copyright - geology_with_helga