SUMMARY / RELATED TOPICS

Limonite

Limonite is an iron ore consisting of a mixture of hydrated iron oxide-hydroxides in varying composition. The generic formula is written as FeO·nH2O, although this is not accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the others being hematite and magnetite, has been mined for the production of iron since at least 2500 BCE. Limonite is named for the Greek word λειμών, meaning "wet meadow", or λίμνη, meaning “marshy lake” as an allusion to its occurrence as bog iron ore in meadows and marshes. In its brown form it is sometimes called brown iron ore. In its bright yellow form it is sometimes called yellow iron ore. Limonite is dense with a specific gravity varying from 2.7 to 4.3. It varies in colour from a bright lemony yellow to a drab greyish brown; the streak of limonite on an unglazed porcelain plate is always brownish, a character which distinguishes it from hematite with a red streak, or from magnetite with a black streak.

The hardness is variable, but in the 4 - 5.5 range. Although defined as a single mineral, limonite is now recognized as a mixture of related hydrated iron oxide minerals, among them goethite, akaganeite and jarosite. Individual minerals in limonite may form crystals, but limonite does not, although specimens may show a fibrous or microcrystalline structure, limonite occurs in concretionary forms or in compact and earthy masses; because of its amorphous nature, occurrence in hydrated areas limonite presents as a clay or mudstone. However, there are limonite pseudomorphs after other minerals such as pyrite; this means that chemical weathering transforms the crystals of pyrite into limonite by hydrating the molecules, but the external shape of the pyrite crystal remains. Limonite pseudomorphs have been formed from other iron oxides and magnetite. Limonite forms from the hydration of hematite and magnetite, from the oxidation and hydration of iron rich sulfide minerals, chemical weathering of other iron rich minerals such as olivine, pyroxene and biotite.

It is the major iron component in lateritic soils. It is deposited in run-off streams from mining operations. One of the first uses was as a pigment; the yellow form produced yellow ochre for which Cyprus was famous, while the darker forms produced more earthy tones. Roasting the limonite changed it to hematite, producing red ochres, burnt umbers and siennas. Bog iron ore and limonite mudstones are mined as a source of iron, although commercial mining of them has ceased in the United States. Iron caps or gossans of siliceous iron oxide form as the result of intensive oxidation of sulfide ore deposits; these gossans were used by prospectors as guides to buried ore. In addition the oxidation of those sulfide deposits which contained gold resulted in the concentration of gold in the iron oxide and quartz of the gossans. Goldbearing limonite gossans were productively mined in the Shasta County, California mining district. Similar deposits were mined near Rio Tinto in Mount Morgan in Australia. In the Dahlonega gold belt in Lumpkin County, Georgia gold was mined from limonite-rich lateritic or saprolite soil.

The gold of the primary veins was concentrated into the limonites of the weathered rocks. In another example the weathered iron formations of Brazil served to concentrate gold with the limonite of the resulting soils. While the first iron ore was meteoric iron, hematite was far easier to smelt, in Africa, where the first evidence of iron metallurgy occurs, limonite is the most prevalent iron ore. Before smelting, as the ore was heated and the water driven off and more of the limonite was converted to hematite; the ore was pounded as it was heated above 1250 °C, at which temperature the metallic iron begins sticking together and non-metallic impurities are thrown off as sparks. Complex systems developed, notably in Tanzania, to process limonite. Nonetheless and magnetite remained the ores of choice when smelting was by bloomeries, it was only with the development of blast furnaces in 1st century BCE in China and about 1150 CE in Europe, that the brown iron ore of limonite could be used to best advantage.

As regards to the use of limonite for pigments, it was one of the earliest man-used materials and can be seen in Neolithic cave paintings and pictographs. Bog iron Iron ore Ore genesis Mineral galleries Mindat Gold and limonite

Circumpolar deep water

Circumpolar Deep Water is a designation given to the water mass in the Pacific and Indian oceans that characterizes a mixing of other water masses in the region. A distinguishing characteristic is the water is not formed at the surface, but rather by a blending of other water masses, including the North Atlantic Deep Water, the Antarctic Bottom Water, the Pacific Intermediate Water masses. CDW, the greatest volume water mass in the Southern Ocean, is a mixture of NADW, AABW, Antarctic Intermediate Water, as well as recirculated deep water from the Indian and Pacific Oceans; because the CDW is a mix of other water masses, its temperature-salinity profile is the point where the TS lines of the other water masses converge. TS diagrams refer to temperature and salinity profiles, which are one of the major ways water masses are distinguished from each other; the convergence of the TS lines thus proves the mixing of the other water masses. Circumpolar deep water is between 1–2 °C and has a salinity between 34.62 and 34.73 practical salinity units.

In recent decades, hundreds of glaciers draining the Antarctic Peninsula have undergone systematic and progressive change. These changes are attributed to rapid increases in regional surface air temperature, but it is now clear that this cannot be the sole driver. A strong correspondence has been discovered between mid-depth ocean temperatures and glacier-front changes along the 1000-kilometer western coastline. In the south, glaciers that terminate in warm CDW have undergone considerable retreat, whereas those in the far northwest, which terminate in cooler waters, have not. Furthermore, a mid-ocean warming since the 1990s in the south is coincident with widespread acceleration of glacier retreat; the conclusion is that changes in ocean-induced melting are the primary cause of retreat for glaciers in this region

Port Kembla railway station

Port Kembla is a single-platform intercity train terminal located in Port Kembla, Australia, on the South Coast railway line's Port Kembla branch. The station serves NSW TrainLink trains travelling north to Sydney; the station serves as a stabling location for South Coast line trains. The wharves and factories that today characterise Port Kembla began to develop in the early part of the 20th century; the railway from the main South Coast line to the new port was completed in July 1916, but the only station, Mount Drummond, was at the northern end. Port Kembla Station, at the southern end near the Outer Harbour breakwater, opened in January 1920. Additional stations were to follow: in 1926 at Cringila, 1936 on the southern boundary of the Australian Iron & Steel steelworks, 1938 within the John Lysaghts site. Electric multiple unit trains began to service Port Kembla Station from February 1986 and the station building was replaced at the same time. Electronic ticketing facilities were activated in 2014.

As a terminal station, Port Kembla features a small stabling yard made up of a platform road, passing loop and engine siding. Port Kembla has one platform, it is serviced by NSW TrainLink South Coast line services from Thirroul. 1 weekday 4 weekend late night services go to Bondi Junction. Premier Illawarra operates two routes to and from Port Kembla station: 43: to Dapto 65: to North Beach Media related to Port Kembla railway station at Wikimedia Commons Port Kembla station details Transport for New South Wales