Zanzibar City vs Cobalt

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Zanzibar City (or Zanzibar Town, often simply referred to as Zanzibar; Swahili: Jiji la Zanzibar; Arabic: مدينة زنجبار‎) is the capital and largest city of Zanzibar, in Tanzania. It is located on the west coast of Unguja, the main island of the Zanzibar Archipelago, roughly due north of Dar es Salaam across the Zanzibar Channel. It also serves as the capital of the Zanzibar Urban/West Region, and qualifies as a district, formally known as Zanzibar Urban District. In 2002 its population was 205,870.Zanzibar City comprises two main parts, Stone Town and Ng'ambo (literally: "The Other Side"); the two areas are historically divided by a creek, now marked by a large street called Creek Road.

Stone Town is the historical core of the city, former capital of the Zanzibar Sultanate; because of its unique architecture and culture, it was declared a UNESCO World Heritage Site in 2000. Ng'ambo is a much larger, modern area that developed around Stone Town after the Zanzibar Revolution, with office buildings and large apartment blocks such as those of the Michenzani neighbourhood.

Source: Wikipedia

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Cobalt is a chemical element with the symbol Co and atomic number 27. Like nickel, cobalt is found in the Earth's crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. Cobalt-based blue pigments (cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was later thought to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment-producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold. Today, some cobalt is produced specifically from one of a number of metallic-lustered ores, such as cobaltite (CoAsS). The element is, however, more usually produced as a by-product of copper and nickel mining.

The copper belt in the Democratic Republic of the Congo (DRC) and Zambia yields most of the global cobalt production. World production in 2016 was 116,000 metric tons (114,000 long tons; 128,000 short tons) (according to Natural Resources Canada), and the DRC alone accounted for more than 50%.Cobalt is primarily used in lithium-ion batteries, and in the manufacture of magnetic, wear-resistant and high-strength alloys. The compounds cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, ceramics, inks, paints and varnishes. Cobalt occurs naturally as only one stable isotope, cobalt-59. Cobalt-60 is a commercially important radioisotope, used as a radioactive tracer and for the production of high-energy gamma rays. Cobalt is the active center of a group of coenzymes called cobalamins. Vitamin B12, the best-known example of the type, is an essential vitamin for all animals. Cobalt in inorganic form is also a micronutrient for bacteria, algae, and fungi.

Source: Wikipedia