Minerals magnetite

The mineral magnetite is a naturally occurring form of Fe304 that has an inverse spinel structure as a result of both Fe2+ and Fe3+ being present. 

The mineral magnetite (Te3()4) contains oxidized and reduced iron, so its reaction,... 

Triiron tetroxide occurs in nature as the mineral magnetite, the magnetic oxide of iron. This mineral along with hematite is used as the starting material for producing iron, steel and other ferro-alloys. 

Triiron tetroxide is obtained from its natural mineral magnetite. In the laboratory the compound may be prepared by adding sodium hydroxide solution to an aqueous solution of 1 2 molar mixture of ferrous and ferric salt. (i.e., 1 mol FeCL + 2 mol FeCls). The resulting black precipitate of the hydroxide on heating dehydrates to gives triiron tetroxide ... 

The mineral magnetite may be characterized from its physical and magnetic properties and by x-ray methods. The iron content in the oxide may be determined by AA, ICP/AES, x-ray fluorescence and other instrumental techniques (See Iron). 

Feldspars may be refractory as well or crystallized from partial melts. Whereas potassium feldspars are found to be mostly refractory, anorthite rich plagioclase may be newly formed. Pyroxene and spinel were identified in varying amounts but no olivine could be detected. Metals and iron oxide minerals (magnetite-hematite) are always present in BA, but have not been quantified yet. In Table 4 the amount and the ranges of measured mineral contents are summarized. 

Insol in w, ale. or eth sol In acids occurs in nature as mineral magnetite. Can be prepd in pure state by dehydrating pptd hydrated ferric oxide, followed by reduction with hydrogen. 

The mineral magnetite is an iron oxide ore that has a density of 5.20 g/cm3. At high temperature, magnetite reacts with carbon monoxide to yield iron metal and carbon dioxide. When 2.660 g of magnetite is allowed to react with sufficient carbon monoxide, the CO2 product is found to have a volume of 1.136 L at 298 K and 751 mm Hg pressure. 

Figure 1.2. Light micrograph of the radula of the chiton Acanthopleura haddoni, showing 46 tooth rows. On the right hand side of the figure the first seven tooth rows are totally transparent (not mineralized), while in the next four rows the first mineral deposits appear. The dark color is due to the iron oxide mineral, magnetite.

Magnetic iron oxide, Fe304, occurs naturally as the mineral magnetite. It has an inverse spinel structure (see Chapter 9) because it contains Fe2+ and Fe3+, and the formula can be written as FeO Fe203. 

Magnetic materials may date back as far as 2,000 B.C., with the first magnetic mineral, magnetite, discovered in ca. 500 B.C. [ present-day magnetic materials are typically alloys containing iron, cobalt, or other lanthanide metals. In Chapters,... 

In 2,000 B.C., magnetic stones are mentioned in the oldest medical textbook ever discovered - the Yellow Emperor s Classic of Internal Medicine. Over 2,500 years ago, a shepherd named Magnes found mineral stones sticking to the metal nails in his sandals he called the mineral magnetite. 

Clarification of the genesis of the main ore minerals (magnetite, hematite, and siderite) is closely related to the solution of the fundamental problem— the origin and conditions of formation of the BIF. If we limit ourselves only to hypotheses in which the iron-formations are interpreted as chemogenic sediments, then it turns out that there are numerous variations in the interpretation of the original composition of these sediments and of the explanation of the conditions of formation of the main ore mineral— magnetite. The main points of modern hypotheses can be summarized in three groups. 

Comparing the data in Fig. 94, it can be suggested that the spread of of the ore minerals of Precambrian BIF was caused by substantial differences in the original oxygen isotopic composition, which makes it possible to use the results obtained to reconstruct the conditions of sedimentation and determine the composition of the iron sediments and the origin of the main ore mineral, magnetite. 

The variations in distribution of oxygen isotopes in the oxides and carbonates of iron-formations have been examined in detail and the complex origin of the main ore mineral—magnetite—has been demonstrated. Isotopic investigations were supplemented by a special study of the chemistry of the rocks of the cherty-iron formations as a whole and of the individual layers, bands, and minerals constituting them. 

Derivation (1) Action of air, steam, or carbon dioxide on iron (2) specially pure grade by precipitating hydrated ferric oxide from a solution of iron salts, dehydrating, and reducing with hydrogen, (3) occurs in nature as the mineral magnetite. 

Ferrosoferric Oxide. Ferric ferrous oxide triiron tetraoxide black iron oxide magnetic iron oxide Ethiops iron. Fe204 mol wt 231.55. Fe 72.36%, O 27.64%. Occurs in nature as the mineral magnetite (red-black lumps). Prepn Gmelin s, Iron (8th ed) part B, 36-62 (1932) Ullmanns EncyklopSdie der Technischen Chemie vol. 6, 420 (1955). Review Robl, ngew. Chem. 70, 367 (1958). 

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