250 
Mineral localities, 
Minerals as rocks, 
Mineral springs, 
Mispickel, 
Molybdenite, . 
Molybdite, 
Monoclinic crystals, optical properties 
of ‘ 
Mountain. cork, 
‘ leather, 
ei meal, 
Motion of bubbles i in rock cavities, . _ 
Mount Carrigain granite, 
Muscovite, . . 
ee biotite granite, 
ee gneiss, . 
66 granite, 
Novaculite, : A é ‘ 
Oil stone, : 
Old eruptive rocks, . 
Oligoclase, 
Olive-green granites, 
Olivine, . 
Olivine, decomposition of 
Olivine diabase, ‘ 
Opal, : 
Optical properties of minerals in sec- 
tions, . 
Optical properties, tabular arrange- 
ment of : : 2 
Origin of rock species, 
Orthoclase, 
Orthoclase and albite interlaminated, 
Orthoclase porphyry, 
Orthorhombic apes optical Prop: 
erties of 
Ossipee granite, 
Outlines of crystals in sections, 
Palatinite, 
Paragonite, 
Pargasite, 
Pebbles flattened between n layers of 
schist, : 
Pegmatite, 
es microscopic 
Pegmatitic granite, 
Penninite, " 
Phyllite, . 
Pinite, 
Plagioclase, “ 
es diorite, . ‘ 
Pleochroism of crystals, . 
Polishing powder, 
Porphyries, P : 
ue classification of 
164, 
222 
INDEX TO PART IV. 
Porphyries, diversity of . 
ee origin of 
Porphyritic diabase, 
ge diorite, . 
as felsite, . 
Porphyrite, 
Porphyry breccia, ‘ 
‘* conglomerate, . 
Portland sandstone, 
Prehnite, ‘ 
Pressure cleavage i in mica, 
Pressure under which granites crys- 
tallized, 183, 
Primal rocks, , c y 
Prochlorite, 
Protogene, 
ne gneiss, 
Pudding granite, 
Purple copper, a 
Pseudo-porphyritic granite 
Psilomelane, 
Pyrite, 
Pyroxene, ‘ 
Eocene and hornblende, relations 
of, ‘ 
Pyroxene crystals i in rock sections, | 
Pyrolusite, , 
Pyrrhotite, 
Quartz, 
us diorite, : 
Quartz-free acag porphyry, 
Quartzite, 
Quartz porphyry, 
“*« schist, 
‘© schist, half fragmental, 
‘* veins, . 
Red diorite, 
‘granite, 
“« sandstone, 
Remarks on basic eruptive rocks, 
i on greenstones, 
Rhodochrosite, zi 
Rhodonite, 
Ripidolite, 
Rock analysis, 
es methods of 
Roofing slate, : 
Rose quartz, 
Roxbury ane 
Rutile, . 
Salts in solution, in rock cavities, 
181, nes 192, 202 
Saussurite, 92 
Scenery among slaty rocks, 238 
Schistose, structure- causes of 210, 212 
