Trass. A kind of tuff or mud poured out by lake craters during eruptions; common in the Eifel, in Germany.
Tufaceous Conglomerate. See [p. 374.]
Tuff. Syn. Trap-tuff, volcanic tuff. See [p. 374.]
Vitreous lava. See [Pitchstone] and [Obsidian].
Volcanic Tuff. See [p. 374.]
[Wacké]. A soft and earthy variety of trap, having an argillaceous aspect. It resembles indurated clay, and when scratched exhibits a shining streak.
Whinstone. A Scotch provincial term for greenstone and other hard trap rocks.
ANALYSIS OF MINERALS MOST ABUNDANT IN THE VOLCANIC AND HYPOGENE ROCKS.
| Silica. | Alumina. | Magnesia. | Lime. | Potash. | Soda. | Iron Oxide. | Manganese. | Remainder. | ||
| Actinolite (Bergman) | 64· | — | 22· | — | — | — | 3· | — | — | |
| Albite (Rose) | 68·84 | 20·53 | — | a trace | — | 9·12 | — | — | — | |
| —— (mean of 4 analyses) | 69·45 | 19·44 | 0·13 | 0·22 | — | 9·95 | a trace | a trace | — | |
| Augite (Rose) | 53·36 | — | 4·99 | 22·19 | — | — | 17·38 | 0·09 | — | |
| —— (mean of 4 analyses) | 53·57 | 1· | 11·26 | 20·9 | — | — | 10·75 | 0·67 | — | |
| Carbonate of Lime (Biot) | — | — | — | 56·33 | — | — | — | — | 43·05 C. | |
| Chiastolite (Landgrabe) | 68·49 | 30·17 | 4·12 | — | — | — | 2·7 | — | 0·27 W. | |
| Chlorite (Vauquelin) | 26· | 18·5 | 8· | — | — | 2· | 43· | — | — | |
| —— (mean of 3 analyses) | 27·43 | 17·9 | 14·56 | 0·50 | 1·56 | — | 30·63 | — | 6·92 W. | |
| Diallage (Klaproth) | 60· | — | 27·5 | — | — | — | 10·5 | — | — | |
| —— (mean of 3 analyses) | 43·33 | 2·2 | 26·41 | 5·58 | — | — | 11·53 | — | 8·54 W. | |
| Epidote (Vauquelin) | 37· | 21· | — | 15· | — | — | 24· | 1·5 | — | |
| Felspar, common (Vauq.) | 62·83 | 17·02 | — | 3· | 13· | — | 1· | — | — | |
| —— (Rose) | 66·75 | 17·5 | — | 1·25 | 12· | — | 0·75 | — | — | |
| —— (mean of 7 analyses) | 64·04 | 18·94 | — | 0·76 | 13·66 | — | 0·74 | — | — | |
| Garnet (Klaproth) | 35·75 | 27·25 | — | — | — | — | 36· | 0·25 | — | |
| —— (Phillips) | 43· | 16· | — | 20· | — | — | 16· | — | — | |
| Hornblende (Klap.) | 42· | 12· | 2·25 | 11· | a trace | — | 30· | 0·25 | — | |
| —— (Bonsdorff.) | 45·69 | 12·18 | 18·79 | 13·85 | — | — | 7·32 | 0·22 | 1·5 F. | |
| Hypersthene (Klaproth) | 54·25 | 2·25 | 14· | 1·5 | — | — | 24·5 | a trace | 1· W. | |
| Labrador-felspar (Klap.) | 55·75 | 26·5 | — | 11· | — | 4· | 1·25 | — | 0·5 W. | |
| Leucite (Klap.) | 53·75 | 24·62 | — | — | 21·35 | — | — | — | — | |
| Mesotype (Gehlen) | 54·64 | 19·70 | — | 1·61 | — | 15·09 | — | — | 9·83 W. | |
| Mica (Klaproth) | 42·5 | 11·5 | 9· | — | 10· | — | 22· | 2· | — | |
| —— (Vauquelin) | 50· | 35· | — | 1·33 | — | — | 7· | — | — | |
| —— (mean of 3 analyses) | 45·83 | 22·58 | — | — | 11·08 | — | 14· | 1·45 | — | |
| Olivine (Klaproth) | 50· | — | 38·5 | — | — | — | 12· | — | — | |
| Schorl or Tourmaline (Gmelin) | 35·48 | 34·75 | 4·68 | — | 0·48 | 1·75 | 17·44 | 1·89 | 4·02 B. | |
| —— (mean of 6 analyses) | 36·03 | 35·82 | 4·44 | 0·28 | 0·71 | 1·96 | 13·71 | 1·62 | — | |
| Serpentine (Hisinger) | 43·07 | 0·25 | 40·37 | 0·5 | — | — | 1·17 | — | 12·45 W. | |
| —— (mean of 5 analyses) | 37·29 | 4·97 | 36·8 | 2·89 | — | — | 3·14 | — | 12·77 W. | |
| Steatite (Vauquelin) | 64· | — | 22· | — | — | — | 3· | — | 5· W. | |
| —— (mean of 3 anal. by Klap.) | 48·3 | 6·18 | 26·65 | — | — | — | 2· | — | 9·5 W. | |
| Talc. (Klaproth) | 61·75 | — | 30·5 | — | 2·75 | — | 2·5 | — | — |
In the last column of the above Table, the letters B. C. F. W. represent Boracic acid, Carbonic acid, Fluoric acid, and Water.