eakle: xanthophyllite in limestone 333 



due to intrusion of, and contact with, this igneous mass. Meta- 

 morphism has been repeated, however, in portions of the rock 

 mass by later injection of dikes and hot solutions, and in conse- 

 quence parts of the hill have been mineralogically enriched 

 by further development of lime-magnesia-silica minerals. The 

 Crestmore waluewite was thickly disseminated in some of the 

 sky-blue calcite of the Commercial quarry on the northeast side 

 of the hill, as indicated by the specimens saved from destruction. 

 It is said that tons of the sky-blue calcite containing the walue- 

 wite were quarried and used for road-making, for sugar refining, 

 and for cement, and in consequence, all of it has disappeared. 



The waluewite occurs mainly as isolated, hexagon-shaped, 

 basal plates of a deep grass-green color. The sizes of the plates 

 vary greatly, some measuring 3 to 4 cm. in diameter and 2 to 3 

 cm. thick. The average size of the crystals is about 5 mm. in 

 breadth and 4 mm. in thickness. The plates are transparent 

 with a brilliant and somewhat pearly luster, but the edges are 

 dull, rounded and grooved, and the measured angles did not 

 approximate any of the forms given by Kohscharof . The plates 

 are very brittle with a hardness of 4-5. The thicker crystals 

 show polysynthetic twinning like the micas, and under the micro- 

 scope they extinguish in striated sectors and give a confused 

 axial figure. The thinner crystals and cleavage plates give a 

 good biaxial figure with an apparent optic angle of ahout 20? 

 Measurements of the optic angle in sodium light showed a 

 variation from 12° to 18? The optic axial plane is (100) and 

 the mineral is optically negative. The refractive indices j3 and 

 7 which lie in the basal section are practically the same and 

 were determined as 1.660. 



Several analyses of the xanthophyllite and waluewite from the 

 Urals have been published and the analysis of the Crestmore 

 mineral agrees with them. 



The associated monticellite is scattered through the calcite 

 as small masses and grains. It appears to be more segregated 

 along the cleavage planes of the calcite rhombohedrons, and is 

 often in close association with the flakes of waluewite and occa- 

 sionally includes the waluewite. One large specimen shows a 



