Manganese, Black Oxide

Synonyms manganese dioxide manganese peroxide black manganese oxide... 

Pigments for use with concrete in the UK should comply with BS 1014. Carbon black, red, yellow, brown and black iron oxides, black manganese oxide, blue cobalt oxide and green chromium oxide are used. 

Black magnetic oxide. See Iron oxide black Black manganese oxide. See Manganese dioxide... 

Such electron-switching means that, like iron, manganese can donate electrons to life and can form the basis of metabolic cycles in underwater sediments. While iron can only change from plus-two to plus-three, manganese can go all the way up to plus-four. This plus-four form of manganese is very reactive and will pull oxygen atoms from its environment to make a blanket of black manganese-oxide crust around the microbe colony. 

A sodium-bearing hydrated manganese oxide of composition Na4Mni4027.9H20. A common constituent of black manganese oxide earths (wad, q.v. Ford, 2001), it is closely related to the mineral todorokite (q.v.). Identifications of this mineral in wad-based pigments may be forthcoming. 

Manganite is a black manganese oxide hydroxide mineral with chemical composition MnO(OH). Its name is derived from its composition and it forms as sub-metallic orthorhombic or fibrous crystals, or with massive form. 

Iron Oxides. In addition to the black iron oxide, there are several natural and synthetic yellow, brown, and red oxides. As a class, they provide inexpensive but dull, lightfast, chemically resistant, and nontoxic colors. The natural products ate known as ocher, sieima, umber, hematite, and limonite. These include varying amounts of several impurities in particular, the umbers contain manganese. Their use is limited because of low chroma, low tinting strength, and poor gloss retention. 

Black dendrites in rocks are formed from manganese oxide depositions. 

Primary clay, for example kaolin, is colorless, and when such clay is heated to a high temperature it produces white ceramic materials. Most pottery, however, is colored its color is due to the fact that most of it was, and still is, made not from primary but from secondary clay. Secondary clay contains minerals other than clay, and colored metal ions in them endow the pottery with their color. Iron ions (in iron oxides), for example, tend to make pottery yellow, brown, or red, and manganese ions (in pyrolusite, a mineral composed of manganese oxide) make it either dark or black. 

About 90% of manganese ore is used in steel smelting. Although there are more than 300 manganiferous minerals, the common ore minerals are largely mixtures of manganese oxides and hydrated oxides. The usual field terms are psilomelane for a hard massive mixture of oxide minerals, pyrolusite for a soft black earthy mixture, and wad for impure, brown earthy oxides and hydrated oxides. LIBS sorting may be effective in this case (Fig. 8.11). 

WAD. The mineral wad, sometimes called bog manganese, occurs in amorphous masses, and consists of mixtures of manganese oxides, MnOi and MnO, and oxides of odter metals such as copper, lead, cobalt, and iron. It is bluish- to brownish-black, usually soft enough to soil the fingers and often porous and light. It is not a distinct mineral species. 

The rate of decomposition at room temperature is very slow. There are substances, however, which will speed up this reaction, one being manganese(iv) oxide. When black manganese(iv) oxide powder... 

Marble is formed from carbonate sediments, the most common of which is limestone. It is composed mostly of calcite. Pure marble is white, but it is easily stained by impurities such as iron oxide (red or brown) or manganese oxide (black). When the grains of calcite in limestone are exposed to heat and pressure, the mineral recrystallizes, forming a dense mass of inter-grown crystals. This makes marble stronger and slightly more dense than its parent rock. 

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