Desert Rose Gypsum. Image by William Josias. (c) Iziko Museums of South Africa
Amethyst mineral. Image by William Joasias. (c) Iziko Museums of South Africa
Cape Granite rocks. (c) Iziko Museums of South Africa
Calcite crystals. (c) Iziko Museums of South Africa
Fishtail twinning in gypsum on display at Iziko South African Museum. Image by William Josias (c) Iziko Museums of South Africa
Large quartz crystals on display at the Iziko South African Museum. Image by William Josias. (c) Iziko Museums of South Africa
Malachite and Azurite minerals. Image by William Josias (c) Iziko Museums of South Africa
Malacite. Image by William Josias (c) Iziko Museums of South Africa
Staurolite. Image by William Josias (c) Iziko Museums of South Africa
Sulphur. Image by William Josias (c) Iziko Museums of South Africa
Wulfenite from Tsumeb, Namibia. Image by William Josias (c) Iziko Museums of South Africa
The Rocks and Minerals Collections at the Iziko Museum of South Africa include a fine collection of calcite, a large collection from the former Tsumeb Mines in Namibia, rhodochrosite, which is found in Hotazel in the Northern Cape as well as diamonds of many different shapes and colours. There is also a unique meteorite collection, including both iron and stony chondrites and a rare carbonaceous chondrite.
Rocks found on earth are composed of an assemblage of minerals. Rocks are divided into three basic groups, namely igneous, sedimentary and metamorphic rocks. Igneous rocks are rocks that form when magma (molten rock) rises to the Earth’s surface and solidifies. Sedimentary rocks form through the coalescence, cementation and subsequent hardening of pre-existing rock and sediment material and are the most common rock type. Table Mountain is made up of Malmesbury Shale below and Sandstone to the top. These rock types are sedimentary. Metamorphic rocks form as a result of changes in pressure and temperature which ultimately leads to alteration of the rock from its present state. Iziko Museums of South Africa houses a wide variety of rock samples providing insight into the earth’s composition and processes both past and present.
Minerals are commonly described as homogenous, naturally occurring solids with a definite chemical composition composed of many different elements such as silicon, calcium, oxygen, etc. and a distinct arrangement of atoms. Rock-forming minerals most commonly form rocks while other types of minerals such as diamonds (gemstones) can be described as commercially valuable minerals. Iziko Museums of South Africa showcases a mineral gallery with a few thousand specimens of many different minerals within the collections itself.
Carbonaceous chondrite: A broad group of chondrite meteorites that include some of the most primitive known meteorites.
Chondrite: Stony (non-metallic) meteorites created when various types of dust and small grains in the early solar system massed or pulled together to form primitive asteroids. They are also the most common type of meteorite that falls to Earth.
Comet: A celestial (i.e. from space) object with a core of ice and dust that forms a ‘tail’ of gas and dust particles when near the Sun.
Meteorite: A solid piece of debris (i.e. made from a variety of rock fragments in space) from such sources as asteroids or comets; it is formed in outer space and survives its impact with the Earth's surface.
Eugene Bergh (Curator)
Telephone: +27 (0) 21 467 7236