Fluorites

IR luminescence lines with relatively short decay times connected with Nd are very strong in the fluorite emission spectrum (Fig. 4.11c,d). Besides that, UV and violet hnes with a short decay time appear, which are ascribed to Nd (Fig. 4.11a,b). 

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Values of M depend upon the structure varying between 1-763 (CsCI) and 2-519 (fluorite structure). 

Rock salt Rutile Caesium chloride Fluorite... 

Fluorite. CaF,. and rutile. TiO,. are minerals in CaFj, each Ca is surrounded by eight F ions, each F by tour C r ions, while in TiO, ihe corresponding co-ordination numbers are 6 and 3. Co-ordination number is generally referred to the cation. 

Fluorine occurs widely in nature as insoluble fluorides. Calcium fluoride occurs as jluospar or fluorite, for example in Derbyshire where it is coloured blue and called bluejohn . Other important minerals are cryolite NajAlFg (p. 141) and Jluorapatite CaFjSCaj (P04)2. Bones and teeth contain fluorides and some natural water contains traces. 

Calcium is a metallic element, fifth in abundance in the earth s crust, of which if forms more than 3%. It is an essential constituent of leaves, bones, teeth, and shells. Never found in nature uncombined, it occurs abundantly as limestone, gypsum, and fluorite. Apatite is the fluorophosphate or chlorophosphate of calcium. 

PUO2 yeUow-green to brown 2400 cubic fluorite 0.53960 11.46... 

Fig. 5. Effect of polymer dosage on different observed properties of flocculated slurry (40). Comparison of five parameters in a flocculation system (8%fluorite suspension + polyacrylamide Cyanamer P250). A, Rate of settling of floe boundary, in cm/s B, height of settled bed, cm C, height of consoHdated filter-cake, cm D, refiltration rate, arbitrary units and E, clarification, % optical transmission of 1 cm of supernatant Hquid after 3 min settling...

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