Geology of solar terrestrial planets is basalt, a denser volcanic rock that is the primary constituent of the ocean floors. Sedimentary rock is formed from the accumulation of sediment that becomes compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form only about 5% of the crust. The third form of rock material found on Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on the Earth's surface include quartz, the feldspars, amphibole, mica, pyroxene, and olivine. Common carbonate minerals include calcite
Samarium mineral samarskite from which it was isolated. The mineral itself was earlier named after a Russian mine official, Colonel Vassili Samarsky-Bykhovets, who thereby became the first person to have a chemical element named after him, albeit indirectly. Although classified as a rare-earth element, samarium is the 40th most abundant element in the Earth's crust and is more common than such metals as tin. Samarium occurs with concentration up to 2.8% in several minerals including cerite, gadolinite, samarskite, monazite and bastnäsite, the last two being the most common commercial sources of the element. These minerals are mostly found in China, the