Silica Percentages of Ignecus Rocks. 
439 
TABULAR STATEMENT ACCOMPANYING Fics. I-VII. 
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SBM ol I) B® 
Cf |ga| a 
Rock Name. PAE = BS S) e Remarks, 
2 ae 
Limburgite 41 | 42-2 | 41-4 
Basalt . 453 | 48:4] 48-5 | Includes: Basalts ; Olivine-, Quartz-, and 
Orthoclase - Basalts ; Olivine-free 
Basalts, Basaltic Glass, Scoria, 
Palagonite and Tachylyte. 
Excludes : ‘‘Alkaline ”’ Basalts (see below); 
Hornblende and Mica-Basalts ; Labra- 
dorites, Variolites, and Andesite- 
Basalts. o 
Dolerite 163 | 51:3 | 50:8 | Includes: Diabase and Dolerite. 
Excludes: Altered Diabase. 
Andesite 455 | 59°5 | 59°5 
Dacite .*. 131 | 65°5 | 65:8 
Rhyolite 275 | 72°6| 73:0 | Includes: Rhyolites, Liparites, and a few 
Acid Pantellerites. 
Trachydolerite 50 | 48-4 | 45:0 
Trachyandesite 27 | 59:1 | 59-0 
Trachyte 163 | 62°5| 640} Includes: Trachytes; Quartz-, Soda-, 
Calcite-Trachytes ; Trachytic Pumice, 
Bombs, Obsidian, and Pitchstone. 
“ Alkaline ” 100 | 40-9 | 40-0 | Incl.des: Hauyne-, Nosean-, Leucite-, 
5 Basalt Nepheline-, Analcite-, Melilite-Basalts. 
Excludes : Tephrites ; Basanites ; 
Nephelinite ; Leucitite ; Hauynophyre ; 
Cecilite. 
Basanite 29 | 45:4 | 44-1 
Tephrite 47 | 48:3 | 47:9 
Phonolite 88 | 56°35 | 56°7 
Gabbro 202 | 48-6 | 48:0 | Includes: Gabbros ; Quartz-, Orthoclase-, 
Micro-, and Essexitic-Gabbros. 
Excludes : Gabbro-Norite, Diorite-Gabbro; 
Gabbro-Diorite, Enstatite-, Bronzite-, 
and Hypersthene-Gabbros. 
Norite . 65 | 50:1 | 50:1 | Includes: Norites; | Gabbro-Norites ; 
Enstatite-, Bronzite-, and Hypers- 
thene-Gabbros. 
Syenite 98 | 58-6 | 60-9 | Excludes: Nepheline-Syenites. 
Granite 643 | 71:2 | 73°8 | Includes : Granites ; Granitites ; 
Adamellites; Microgranites; Grano- 
phyres; Graphic Granites ; Rapakivi 
Granites; Alaskite-Granites; Paisan- 
ites ; Charnockites. 
Excludes: Granodiorites. 
All Diorites 142 | 52:°9|. —-| Excludes:  Quartz-Diorite; Tonalite ; 
“ European ”’ 53 | — | 51°5 Gabbro-Diorite ; Diorite-Gabbro. 
Diorites 
“ American” do.| 83 | — | 57:0 
Monzonite . 50 | 56°3 | 56:3 
Quartz-Diorite 
and Tonalite | 98 | 60:3 | 59:5 
Grano-Diorite . 52 | 64°5 | 65°9 
Essexite 44 | 47:1| 46°8| Hacludes: Essexite-Gabbros, -Dolerites, 
-Lavas, -Diabases, and -Porphyrites ; 
Diorite-Essexites. 
Nepheline 116 | 56:2 | 54:9 | Includes: Foyaite; Litchfieldite; Ditroite; 
Syenite Laurdalite; Sodalite-; and Leucite- 
Syenite. 
