Snipfact:

    Minerals are naturally occurring substance with a definite chemical composition. Most mineral names end in “ite”. Many have a practical use or contain a chemical compound or element that can be extracted and used commercially. Bauxite, for instance, is the main source of aluminium. Gems are minerals that are highly prized for their rarity or appearance, e.g. diamonds, sapphires, emeralds and rubies.

    The rock formerly known as Ayers Rock in Northern Territory, Australia, is believed to be the world’s largest free-standing rock. It is made of sandstone and is 335 m (1,100 ft) high, 3.6 km (2.2 miles) long and 2 km (1.5 miles) wide. It was originally called after South Australian premier Sir Henry Ayers, but it is now known by the name given to it by local Aborigines, to whom it is scared.

  There are three categories of rock- igneous, sedimentary and metamorphic .   Igneous rocks originate deep in the Earth. They erupt from volcanoes as magma and cool or solidify as they rise to the upper layers. Basalt is an igneous rock and so is granite, a very hard rock often used in building . Pumice stone is a soft igneous rock that is ejected from volcanoes. As it cools, it often fills with so many air bubbles that it floats in water.   Sedimentary rocks can be formed by deposits in water and occasionally by wind. Sandstone is a common example. Organic sedimentary rocks are formed by living plants and animals – coal comes from plant matter and limestone from the  calcium from billions of plants and animals. chemical sedimentary rocks occur when chemical processes take place and minerals are deposited. Metamorphic rocks are Igneous or sedimentary rocks that have changed as a result of high temperatures or pressures. State used on roofs is a familiar ...

  The Mohs scale, named after German mineralogist Friedrich Mohs (1773-1839), is used for comparing the relative hardness of minerals. Each minerals on the scale can be scratched by the harder ones below it.     Mohs scale No              Substance 1                Talc 2                Gypsum 3                Calcite 4                Fluorite 5                Apatite 6                Orthoclase 7         ...

    Many meteorites land in the sea and in unpopulated areas so they are never seen. The Hoba meterorite, the largest in the world, was found in Namibia in 1920. It measure 2.73 x 2.43 m (9 X 8 ft) and is 82 per cent iron and 16 per cent nickel. It weighs more than 60 tonnes.     Second largest is the Tent, found in Greenland in 1894 and now known by its original Eskimo name, Ahnighito. This meteorite weighs about 57.3 tonnes and is on display in the New York Museum of Natural History.

  About 500 meteroites reach Earth every year. Many collision sites have been altered by weather over millions of years, and scientists are unsure whether some craters are actually the craters of extinct volcanoes. Those below are all agreed to be meteorite craters.  1 Verdefort, South Africa 300 km (186 miles) in diameter 2 Sudbury, Ontario, Canada 250 km (155 miles) in diameter 3 Chicxulub, Yucatan, Mexico 170 km (106 miles) in diameter 4 Manicougan, Canada 100 km (62 miles) in diameter 5 Popigal, Russia 100 km (62 miles) in diameter