Orthoclase

Engels and fngamells reported the following results for the %w/w K2O in a mixture of amphibolite and orthoclase. ... 

K2SO-2 MgSO, and halite and (5) kainite ore, kainite [1318-72-5] 4(KC1 MgSO -11H20, and halite. More than 90% of the estimated potassium reserves occur principally as sylvinite and camaUitite (107). Sylvite, the richest of the minerals at 63% K2O, is the principal economically exploitable reserve. In addition, there are four principal insoluble potassium sUicate minerals, glauconite, leucite, nepheline, and orthoclase—sanidine which range in K2O content from 7 to 22%. These minerals are plentihil but for economic reasons may never be exploited for potassium. 

Intermediate Hardness (4) Fluorite, soft phosphate, magnesite, limestone (5) apatite, hard phosphate, hard limestone, chromite, bauxite (6) feldspar, ilmenite, orthoclase, hornblendes. 

The hardness of an enamel surface is an important property for such items as enamelled sink units, domestic appliances, washing machine tubs which have to withstand the abrasive action of buttons, etc. On Moh s scale most enamels have a hardness of up to 6 (orthoclase). There are two types of hardness of importance to users of enamel, viz. surface and subsurface. The former is more important for domestic uses when one considers the scratching action of cutlery, pans, etc. whereas subsurface hardness is the prime factor in prolonging the life of enamelled scoops, buckets, etc. in such applications as elevators or conveyors of coal and other minerals. 

Icenhower and London (1996) data give values of which increase linearly with the molar fraction of orthoclase component (Xo) (Fig. 19). A weighted fit gives ... 

Figure 19. Variation in dimension of the X-fold cation site in alkali-feldspar for 2+ cations (), obtained by fitting the experimental data of Icenhower and London (1996) for Dca, >sr and Dsa at 0.2 GPa and 650-750°C. In performing the fits was set at 91 GPa for all runs. Error bars are 1 s.d. The positive slope is consistent with measured changes in metal-oxygen bond length from albite to orthoclase (cf Fig. 6). The solid line shows the best-fit linear regression given in Equation (35).

Orthoarsenic acid, 3 264—265 Orthoboric acid, 4 242t, 249—255 Orthoclase, hardness in various scales, l 3t Orthocortex, in wool fibers, 11 173 Orthodontics, superelastic and pseudoelastic SMA devices in, 22 350-351 Orthoesters, 10 498 Orthoferrites, 11 56t, 57 Orthogonal matrices, 6 27 ort/io-hydrogen, 13 759, 760—761 Orthokinetic flocculation, 11 631 22 56 Orthokinetic flocculator, 22 59 Orthomyxoviruses, 3 136—137... 

Figure 8.22 Closure temperature Tc as a function of the rate of loss for a spherical geometry [equation (8.7.6)]. The numbers on the curves are for different fractions lost by the mineral. Amphibole data from Harrison (1981), orthoclase data from Foland (1974). Points A, A, B, B see text.

Foland, K. A. (1974). Ar40 diffusion in homogeneous orthoclase and an interpretation of Ar diffusion in K-feldspars. Geochim. Cosmochim. Acta, 38, 151-66. 

Potassium feldspar (orthoclase) Muscovite mica Quartz Felsic (rhyolite granite)... 

Table 5.62 Chemical analyses of some natural feldspars (Deer et al., 1983). (1) orthoclase (Mogok, Burma) (2) Adularia (St. Gottard, Switzerland) (3) anorthoclase inclusion in augite (Euganean Hills NE Italy) (4) sanidine from a nepheline-leucitite (5) albite from a pegmatite (6) anorthite from a calc-silicatic rock. ...

Figure 5.58 Phase stability relations in (pseudo) binary system NaAlSi308-KAlSi308 at various P and T conditions (Le = leucite Or = orthoclase Sa = sanidine L = liquid V = vapor). Here, orthoclase identifies simply an intermediate state of substitutional disorder.

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