Malachite after Azurite

Unknown Owner

An interesting antique specimen from this old famous Russian locality. Crystals of what were once blocky azurite measuring to almost 1.0 cm in size and now replaced by green crystallized malachite are nice across the top of a matrix with blue massive azurite and green massive malachite. This is in good condition. The specimen comes with an antique label as shown at the end of the video and dates to the very early 20th century, if not earlier.Nizhnii Tagil, located on the eastern slopes of the Ural Mountains in the Sverdlovsk Oblast of Russia, is a world-class mineralogical site situated within a complex geological suture zone. The region is famous for its massive contact metamorphic deposits, or skarns, which formed when Paleozoic igneous intrusions reacted with surrounding limestone and volcanic rocks. This intense geological activity created the legendary Mednorudyanskoye copper deposit, which is hosted within a weathered, oxidized zone above primary sulfide ores. Historically, the site was discovered in the early 1700s under the reign of Peter the Great and became the industrial heart of the Demidov family empire. For over two centuries, it served as a premier global source of high-grade copper and iron, while simultaneously producing some of the most magnificent ornamental malachite ever discovered, much of which now adorns the palaces and cathedrals of Saint Petersburg.A pseudomorph is a mineralogical phenomenon where one mineral replaces another in such a way that the internal chemistry changes while the original external crystal shape is perfectly preserved. This "false form" occurs when a pre-existing crystal becomes unstable due to changes in temperature, pressure, or chemical environment, allowing a new mineral to slowly take its place. In the case of malachite after azurite, the process involves a chemical transition where the deep blue azurite loses carbon dioxide and gains water to transform into the stable green malachite. The result is a specimen that looks exactly like a sharp, bladed or tabular azurite crystal but is composed entirely of vibrant, velvety green malachite.