G. F. Kunz — Mineralogical Notes. 479 



2. Crystals of Hollow Quartz from Arizona. 



These crystals are found about 3 miles southwest of the 

 town of Pinal, in Pinal Co., Arizona. They occur in a sand- 

 stone which has been traced for about one mile ; it is penetra- 

 ted in many places by spherules of obsidian ■§■ to 3 inches 

 across, which cover the ground like a shower of large hail- 

 stones. These quartz crystals are of exceptional interest from 

 the fact that they are mere walls surrounding hollow spaces 

 much larger than the area of the wall itself (see figures on ad- 

 joining cut). In some instances the crystals radiate from a cen- 

 tral point; numbers of the detached crystals show this very 

 strikingly. At the point of attachment there often appear 

 small nuclei of chalcedony, and in some instances, the crystals 

 radiate from this chalcedonic center so as to form true quartz 

 flowers, as shown in the second figure. Quite often they 

 are single individuals hollowed out, leaving only the smallest 

 edges of what ought to be a pyramid, and the interior of the 

 crystal being hollow to the base in a few instances. They are 

 not cavernous like the Poretta, Italy, and Burke Co. quartz. 

 As hollow quartz their characteristics are sufficiently marked 

 to isolate them from those found at any other locality. 



It is very evident that they are the result of a crystallization 

 from a solution, and the chalcedony being rounded and coated 

 white, has every appearance of stalagmitic growth, fading imper- 

 ceptibly into quartz. In some few instances the quartz crystals 

 have a coating of chalcedony at their terminations. The sides 

 of the prismatic faces are striated and have all the unevenness 

 of those made up of crystalline plates. The hollow crystals 

 themselves are usually made up of six flat individuals so sym- 

 metrically arranged as to leave the center hollow, the whole, 

 often being one distinct crystal. Many of the crystals are ter- 

 minated with the pyramid face R only; — 1, when present, is 

 usually very small and only slightly developed. Some, how- 

 ever, have both R and — 1. In general appearance they resemble 

 the amethyst of Schemnitz, Hungary. The figures were all 

 carefully drawn and are of the natural size. 



In this connection it may be mentioned that from near 

 Crouch's Mill, Gaultney's township, Alexander Co., North 

 Carolina, the writer obtained a beautiful group of quartz radia- 

 ting from one of these chalcedonic nuclei and forming a com- 

 plete flower that measured 7 cm across. None of these crystals, 

 however, were hollow. 



3. Hydrophane from Colorado. 



A white opaque variety of hydrophane, in rounded lumps, 

 from 5 mm to 25 mm in diameter, with a white, chalky or glazed 

 coating somewhat resembling the cacholong from Washington 



