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MR. H. H. ARNOLD-BEMKOSE ON A QTJARTZ-ROCE: [May 1 898, 



Nos. 533 & 534, 2 inches below 533. The base is of a cloudy or 

 crystalline calcite, through which the quartz-crystals are irregularly 

 distributed. Numerous small veins or strings of quartz traverse 

 the slice. The grains are often smaller than the separate crystals. 

 The veins have a structure similar to that of the quartz-rock, and 

 often run a tortuous course. A foraminifer replaced by calcite is 

 penetrated by a quartz-crystal. 



No. 747, about 4 feet below 534, is a foraminiferal limestone 

 partly replaced by calcite. Quartz-crystals are scattered through, 

 the slice, and sometimes penetrate a foraminifer. The slice is 

 traversed by several small veins, which consist of separate quartz- 

 crystals, and a quartz-aggregate similar to the quartz-rock. The 

 grains vary much in size and often interlock. The outer crj'stals are 

 arranged in various positions with regard to the boundary of the 

 vein. 



No. 748, about a foot below 747. The base consists of cloudy or 

 crystalline calcite, without any trace of organisms. The quartz 

 sometimes is in separate crystals, but most commonly in aggregates 

 or groups irregularly distributed. The component grains vary in 

 size. A vein of crystalline calcite traverses the slice. 



(c) 100 feet north of (b) and in tlie same field. 



About 100 feet north of the chert-quarry and in the same field 

 is an outcrop, measuring about 6 feet in length by 5| feet in height, 

 consisting of quartz-rock and quartzose limestone. 



No. 428, sp. gr. 2*54, consists of fluor and quartz, the latter 

 predominating. In some parts of the thin slice the individual 

 quartz-crystals are embedded in fluor, and in other parts fluor is 

 absent. The last-named mineral is irregularly distributed, has a faint 

 violet tint, possesses traces of cleavage, and always remains extinct 

 between crossed nicols. 



No. 539, 3 feet to the right of 428. 

 ]No. 427, 6 feet ditto. 

 No. 536, 2 feet below 428. 

 No. 426, 2 feet below 637. 



These four specimens are similar, and 

 consist of quartz in a cloudy or 

 crystalline calcite. 



The quartz is sometimes in idiomorphic crystals, which give a 

 hexagonal cross-section, but is more often in groups of crystals 

 which have interfered with one another's growth. Many of them 

 contain zones of calcite, which in some cases mark the previous 

 boundaries and in others are parallel to the present boundaries of 

 the crystal. 



No. 427 contains a large quartz-crystal with three zones of calcite. 

 Small portions of two of the hand-specimens were dissolved in 

 dilute hydrochloric acid. The residue of No. 426 consisted entirely 

 of crystalline quartz, often in groups or clusters of crystals. Few 

 of the separate crystals had perfect crystalline boiindaries. The 

 largest was '5 x '15 mm. The residue of No. 427 was similar and 

 contained fragments of fluor. The crystals of quartz varied in size 



