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Limestone ( calcium carbonate CaCO3) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of CaCO3. Limestone forms when these minerals precipitate out of water containing dissolved calcium.
There are two main types of trebuchet. The first is the traction trebuchet, or mangonel, which uses manpower to swing the arm. It first appeared in China by the 4th century BC. It spread westward, possibly by the Avars, and was adopted by the Byzantines, Persians, Arabs, and other neighboring peoples by the sixth to seventh centuries AD.
The Rosetta Stone is a stele of granodiorite inscribed with three versions of a decree issued in 196 BC during the Ptolemaic dynasty of Egypt, on behalf of King Ptolemy V Epiphanes. The top and middle texts are in Ancient Egyptian using hieroglyphic and Demotic scripts, respectively, while the bottom is in Ancient Greek.
Asbestos ( / æsˈbɛstəs, æz -, - tɒs / ass-BES-təs, az-, -toss) [1] is a naturally occurring fibrous silicate mineral.
Göbekli Tepe ( Turkish: [ɟœbecˈli teˈpe], [2] 'Potbelly Hill'; [3] Kurdish: Girê Mirazan or Xirabreşkê, 'Wish Hill' [4]) is a Neolithic archaeological site in the Southeastern Anatolia Region of Turkey. The settlement was inhabited from c. 9500 to at least 8000 BCE, [5] during the Pre-Pottery Neolithic.
Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, but diamond is metastable and converts to it at a negligible rate under those conditions.
Steve Austin (born Steven James Anderson; December 18, 1964), better known by his ring name " Stone Cold " Steve Austin, is an American retired professional wrestler, media personality and actor.
