PETKOf:iiAlMIY. 345 



Chki.ius, C. Dio laiiiprDpliyiisclicii und ^raMitpoi-pliyrisclimi G;in<j;ge8tein«! iiii 



Grnii(lgel)irgc des Spo.ssarts und Odciiwalds. Nfiies Jjihrli. Miii., (ieoL, (^tc, 



1888, II. Biind, Erstes I left, p. (J7. 

 ClauKE, V. W., and Mkhhili,, Gkohgic P. On Nephrite and .ladeile, Pioc. U. S. 



Nat. Museiiin, 1888, ]>. lir>. 

 CoHKN, E. Andahisitriilircndf. (iraiiilc Nt'iics Jaluh. ISIin., (jt'ol., etc., 1887, ii. 



Build, p. 178. 

 Calls atttiiit ion to tin- occnncncc of micidscnpic andaliisite in tlui granites of 



Klaiise and lianliniiin/,a(di in tlic. Scliwai/wald ; in lioclicsson, Dopartnicnt of 



Vo.sges; Mos/.laviua, Croatia; and other localities. 

 CoLK, Gkenvili.E a. J. Tht5 lihyolites of Wnenheiin, Vosg(!s. Geol. Mag., July, 



1887, p. 299. 



Un soiiio additional occnriuMiees of 'i'achylyte. (,)Mar. .Tom-. (Jeol. Soc, No. 171, 



May, 1888, vol. xliv., p. 3(K). 



Descriltes the occunence of t.-ichylyte in Ardtiin, in Mnll : Kilmelfort, iu Ar- 

 gyle ; Bryansford, County Down, in Ireland ; and among certain older rocks of 

 the Welsh border. One plate, with six lignres, showing nii(Mo-stnictnres. 

 Collins, J. II. On the Geological History of thcCoi'uish 8erp(!ntin()us Kocdis. Geol. 

 Mag., May, 1887, p. 220. 



Concludes that these are altered olivine, liornhlende, or angite rocks. 

 Chkustchoek, K. von. Beweis flir den urspriinglieh hyalin-niagniatis<;ha.n Zustand 

 gewisser echter Granite und granitartiger (iesti-ine. Nenes .lalirh. Min.,Geol., 

 etc., 1887, I. Baud, zweites Ht^ft, p. 2(IS. 

 Ckosby, W. O. Qnartzites and Siliceous concretions. Tech. Quarterly, May, 16SS, 

 pp. :{77-407. 



Discusses the origin of the, secondary silica in qnartzites and of the chaleedouic 

 nodules in calcareous rocks. 



Geology of the Outer Islands oi' Boston II;irli(U'. Proc. Boston Soc. Nat. His- 

 tory, 1887, vol. XXIII, p. 4.50. 



Cuoss, WiiiTM.xN. Geology and Miuiug Industry of Leadville, Colorado. Appendix 

 A. Petrography, Mouograph xii, U. 8. Geol. Survey, pp. IU9-:558. Two luU-pago 

 l)lates showing micro-structure. 



The rocks described are quartz-porphyries, diorites, porphyrites, rliyolites, 

 trachytes, and audesites. One of the more interesting rocks of the series is the 

 nevadite variety of the rhyolite. The saiiidins of this rock often show a beauti- 

 ful satiu-like luster, which is shown to be " duo to the interference of light in 

 passing tiluis of air between the extremely thin plates," into which the crystals 

 are divided by a series of partings parallel to the lustrous surface. Drus}' cavi- 

 ties iu the rock contain topaz iu very i)e,rfectly developed forms. The audesites 

 are in part hypersthenic, as previously described in Bull. No. 1, IT. S. Geological 

 Survey. The <|uartz porphyries frequently carry the mineral allanite. 



CROS.S, Whitman. Notes on the lleury Mountain Rocks, Geol. aud Min. Industry 

 of Leadville, Colorado. Mouo. xii, U. S. Geol. Survey, pp. 359-:?62. 



The rocks are hornbljDndic and augitic porphyrites and are briefly noted for 

 purposes of comparison with the rocks of the Leadville region. 



• Notes ou Phonolite from Colorado. I'roc. Colo. Sci. Soc, 1887, pp. 107-174. 



This paper is of particular interest as describing the second occurreuee of 

 phonolite yet kuowii iu the United States.* The rock Las not as yet been found 

 in situ., but iu the form of bowlders of " local oiigiu," aud " apparently derived 

 from the hills to the soutiiward," and on the eastern slope of the Haydcni 

 divide. 



* The only other known locality for this rock iu the United States is the Black Hills 

 of Dakota, where it was described by Caswell in 1880. 



