Online Encyclopedia
Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.
MONAZITE
Online EncyclopediaEncyclopedia Home :: MOL-MOS
del.icio.us it!
|
MONAZITE , a See also:mineral consisting of anhydrous phosphate of the See also:cerium metals (Ce, La,Di)PO4, together with small and variable amounts of See also:thorium (ThO2, 1-1o%) and See also:yttrium. It is of considerable commercial importance as a source of thoria for the manufacture of the Welsbach and other mantles for incandescent See also:gas-See also:lighting: the cerium is used to a limited extent in See also:pharmacy.
The following analyses are of monazite from: (I.) See also:Burke See also:county, See also:North Carolina; (II.) See also:Arendal, See also:Norway; (III.) Emmaville, See also:Gough county, New See also:South See also:Wales.
I. II.
29.28 27.55
31.38 29.20
30.88 26.26
3'82
6.49 9.57
1.40 1.86
1.13
0-69
0.20 0.52
99.63 too•6o 95 00
Specific gravity . . . 5.10 5.15 .1
Thoria and See also:silica being often See also:present in the molecular ratio t : t, it has been suggested that they exist as See also:thorite (ThSiO4) as a See also:mechanical impurity in the monazite.
Crystals of monazite belong to the See also:monoclinic See also:system, and are usually flattened parallel to the ortho-pinacoid (a in the figure). The large (up to 5 in. in length) reddish-See also: Breithaupt in 1829, and named by him from Gr. yova('ew, to be solitary, because of the rarity of the singly occurring crystals. The hardness is 5z, and the specific gravity 5.1-5.2. See also:Light which has traversed a crystal or See also:grain of monazite exhibits a characteristic absorption spectrum, and this affords a ready means of detecting the mineral. As See also:minute idiomorphic crystals monazite is of wide See also:distribution in granites and gneisses, being present in very small amounts as an See also:accessory constituent of these rocks. By powdering the See also:rock and washing away the lighter minerals in a stream of See also:water the heavy minerals (See also:zircon, See also:anatase, See also:rutile, See also:magnetite, See also:garnet,monazite, xenotime, &c.) may be collected. This separation has been effected naturally by the weathering and disintegration of the rocks and the See also:accumulation of the heavier minerals in the beds of streams. Under these conditions monazite has been found as rounded water-worn grains in the alluvia] See also:gold-washings of the Urals, See also:Finland, See also:Siberia, the See also:United States, See also:Brazil, See also:Colombia, New South Wales, &c., and in See also:tin-gravels in See also:Swaziland, South See also:Africa. Larger crystals of monazite are found embedded in See also:pegmatite See also:veins in the Ilmen Mountains (See also:southern Urals); at Arendal and other places in southern Norway, where it is collected in the feldspar quarries to the extent of about one ton per annum; and in the See also:mica mines at See also:Villeneuve in See also:Quebec, where masses of monazite weighing 20 lb have been found. The small crystals of the "turnerite " habit occur implanted, often with anatase and rutile, on the crystallized See also:quartz and See also:albite, which See also:line crevices in the crystalline See also:schists of the See also:French, Swiss and Tirolese Alps; similar crystals with the same associations occur very exceptionally in the See also:clay-See also:slate at See also:Tintagel in See also:Cornwall. Microscopic crystals of monazite (cryptolite, from Kpvlrros; concealed) have been observed embedded in the crystallized See also:apatite of Arendal in Norway. The deposits worked commercially are the monazite-bearing sands of North Carolina and Brazil, and to a smaller extent those of South Carolina. In North Carolina it occurs over a wide See also:area in the streams rising in the South Mountains, an eastern outlier of the See also:Blue See also:Ridge. The rocks of the See also:district are granitic biotitegneiss and See also:hornblende-See also:gneiss, and are intersected by veins of auriferous quartz. The percentage of monazite in the See also:river-gravels varies from very small amounts up to 1 or 2 %. The heavy minerals contained in the gravels are collected in the same manner as in washing for gold (which is often also present) ; magnetite is separated with a magnet; but other minerals, such as zircon, rutile, garnet, See also:corundum, &c., cannot be separated by mechanical means. The product is a See also:fine-grained yellowish See also:sand containing 65-85% of monazite and 3-9% of thoria. In Brazil it occurs in river-gravels and also in the sand on the See also:sea-beaches; an extensive accumulation of very See also:rich monazite sand occurs on the seashore near Alcobaca in See also:Bahia, and this has been shipped as See also:ballast in the natural See also:state. See H. B. C. Nitze, " Monazite " (16th See also:Annual See also:Report of the United States See also:Geological Survey, pt. iv. (1895), pp. 667-693). (L. J. Additional information and CommentsThere are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML. Site content, images, and layout Copyright © 2006 - Net Industries, worldwide. |
|
|
[back] MONASTIR, or BITOLIA |
[next] MONBODDO, JAMES BURNETT, LORD (1714-1799) |