96 



EXCUESION IY. 



THE WAYSIDE MUSEUM. 



48. THE student of geology will make but little progress 

 in this delightful science without a thorough practical ac- 

 quaintance with the mineralogical distinctions of rocks. He 

 must first know a few of the common minerals quartz and 

 its varieties, as rock-crystal, amethyst or purple quartz, 

 smoke quartz or cairngorm, hornstone, jasper and pitchstone ; 

 felspar and its varieties, as glassy and compact felspar and 

 albite ; mica, talc, chlorite, serpentine, hornblende, hyper- 

 sthene, augite, olivine, and calcspar. All these are "simple 

 minerals" to the mineralogist; the chemist calls them "com- 

 pound," since he can resolve them into elements. Using, 

 then, the terms simple and compound, in the mineralogical 

 sense, we divide the rocks into two classes; common slate, 

 limestone and the marbles, coal, quartz rock, and serpentine, 

 are the simple rocks; all others, forming by far the greatest 

 proportion of the mountain rocks of the globe, are composed 

 of two or more of the five simple minerals quartz, felspar, 

 mica, hornblende, and augite. Knowing these, the student 

 will easily make out the composition of almost all the rocks, 

 certainly all those of Arran. With every term a definite 

 idea will then be connected, and the study of the subject will 

 be smooth and pleasant henceforward. Arran has been called 

 an epitome of the globe; our Wayside Museum is an epitome 

 of Arran, in so far as a collection of rocks is concerned. In 

 a few visits to this collection, the student will gain a know- 

 ledge of rocks, which he could never acquire from the hand- 

 specimens in a common collection a knowledge absolutely 

 necessary to all true progress in the science. 



49. The collection of rocks which we designate as the 



