Ball bracelet 10mm from Lava from Italy.

Lava is rock in liquid form. After magma reaches the Earth's surface or seabed, it is called lava. Due to differences in magma composition, flow rate, temperature and chemical, mineralogical composition, there are several types of lava, each with its own behavior and characterized by a porous structure. Lava can have a destructive effect, but at the same time it also has a creating effect. For example, new land can be formed by lava, which, for example, created the Hawaiian islands in the Pacific Ocean. Furthermore, cooled lava - after several centuries of weathering - is very fertile and can therefore be used as agricultural land. The word 'lava' originally comes from the Italian language, and is probably derived from the Latin word labes, which refers to the sliding or sliding of lava. The word was first used in its current meaning by Francesco Serao, professor of medicine at the University of Naples, when he described the eruption of Mount Vesuvius in the period from May 14 to June 4, 1737. Serao believed that lava was a mixture of sand and earth that had been melted by the heat of the volcanic fire. He described "a flow of fiery lava" compared to the water and mud that flow from the volcano after heavy rain. Cooling viscous lava often accumulates in a volcanic shaft. This blockage and the presence of gases in the lava build up pressure in the shaft. Eventually, an eruption occurs, creating large clouds of volcanic ash and gas, as well as pyroclastic flows. The most explosive eruptions are followed by a calmer period during which lava is emitted. If the lava is rich in silica, a slowly growing lava dome is formed, a large pillow-like structure full of cracks and crevices. The top and edges of a lava dome are usually covered with rock fragments, breccia, and ash. The hardened rock that forms from lava is called effluent rock. The appearance and composition of different effluent rocks varies greatly. If a lava flow of rhyolite cools quickly, it can become obsidian. However, if it is filled with gas bubbles it can also become pumice. When the same lava slowly cools, it becomes a light-colored solid rock that is simply called rhyolite.