Mineral crystals grow under a variety of conditions. Slow cooling of magma (melted rock) deep within the Earth generally leads to a rock such as granite with visible crystals of feldspar, quartz, mica, amphibole and other minerals. Water in the magma can even facilitate pegmatite formation. Pegmatite is an igneous rock composed of mineral crystals generally with a diameter of several centimeters which, on rare occasions, can be meters.
Fuchsite Green Mica Rock Mineral Specimen 1.5 Inch w Info Card
Blue Biggs Jasper stone. Blue Biggs Jasper is a silicated volcanic ash. It was formed during a volcanic eruption and is part of a Miocene series of rocks called the John Day Formation, near Biggs, Oregon, USA. It is a decorative stone used for jewellery and trinkets.
Cherry blossom stones are relatively small, subhexagonal-shaped masses of fine-grained muscovite mica that show a flower-like pattern in transverse cross-section. They're found in a matrix of hornfels, a fine-grained, contact metamorphic rock. Hornfels forms by intense heating & chemical alteration of shales by nearby lava or magma. #nature #rock #mineral