454 



MINERALOGY 



Tetragonal Equatorial; c = .4384; 001 A 101 = 23 40'; Com- 

 mon forms, a (100), c (001), m(110), e (101), h (210) ; Cleavage, 

 a and m distinct; Brittle; Fracture, uneven; H. = 5-6; G. = 

 2.66-2.73 ; Color, white, gray, shades of yellow, green, red, brown 

 to black; Streak, white or pale; Luster, vitreous to pearly; 

 Transparent to opaque; o> = 1.562; e = 1.546; o> = .016; 

 Optically (-). 



B.B. Fuses easily with intumescence to a blebby glass. The 

 fused mass powdered gelatinizes with HC1. 



General description. Crystals coarse prismatic, combination 

 of the two prisms a and m terminated by the unit pyramid or the 

 two unit pyramids. The third order prism h (210) and the pyra- 

 mid z (311) occur on crystals 

 from Grass Lake, New York. 

 Wernerite is often granular or 

 massive. 



In sections the scapolites are 

 colorless, either in crystalline 

 outline or rounded grains ; pris- 

 matic cleavage cracks distinct; 

 relief is very low, about that of 

 quartz. The inclusions are not 

 characteristic ; double refraction 

 rather strong, yielding interfer- 

 ence colors. of the second order 

 and increasing with the amount 

 of calcium present. The inter- 

 ference figure is found in the 



sections in which the cleavage cracks are at right angles, yielding 

 a dark cross with color bands in thin sections, in the margin of 

 the field only. Optically negative. The scapolites are found in 

 igneous rocks as secondary minerals only. They are the products 

 especially of contact metamorphism and commonly occur in 

 granular limestones, where they are associated with pryroxene, 

 hornblende, zircon, spinel, titanite, and garnets. 



Wernerite occurs in fine crystals at Pierrepont, Gouverneur, 

 Monroe, and Amity, New York, and at numerous points in New 

 Jersey, Pennsylvania and the New England States. 



Meionite and mizzonite occur in the ejected blocks of limestone 

 on Monte Somma, Vesuvius. 



FIG. 488. Wernerite. Laueinpaei, 

 Finland. 



