64 CORUNDUM^ ITS OCCURRENCE AND DISTRIBUTION. 
iiepheline-syenites a nearly transparent corundum of gem quality 
has been found. A further description of these deposits and the 
names of the companies operating corundum deposits are given on 
pages 151-153. 
CORUNDUM IN QUARTZ-PORPHYRY. 
The only instance of corundum in quartz-porphyry that has been 
noted is that described l)y Von Foullon " from Teplitz, in Germany. 
After subjecting the rock to the action of hydrofluoric and sidphuric 
acids an insoluble residue was obtained consisting of small grains of 
corundum. 
CORUNDUM IN TRACHYTE. 
Hussak ^ described corundum from the trachytic bombs of the vol- 
canic region of the Laacher See, in Germany. Porlig '^ found green 
corundum in a bom!) from the trachyte-tuffs of Konigswinter ; and 
Dana '^ mentions a similar occurrence in bombs at N-iedermendig. 
CORUNDUM IN BASALT. 
Besides the occurrence of corundum in metamorphosed inclusions 
ill the volcanic rocks of the Auvergne, France, Lacroix ^ also found 
the mineral extensively in the rocks themselves, trachytes, andesites, 
basalts. Similar mineral associations, both in the inclusions and in 
the volcanic rocks, are described by Dannenberg ^ in the trachytes, 
andesites, and basalts of the Siebengebirge, Germany. 
CORUNDUM IN CONTACT ZONES AND INCLUSIONS. 
Busz ^ has also observed corundum as a contact product of granite 
on clay-slate at Dartmoor, in Devonshire, Enghmd. Barrois '' 
describes banded violet and green hornstones produced by meta- 
morphism in granite at Pont-Paul, near Morlaix, in Finisterre, 
France. The violet layers consist of biotite, magnetite, pleonaste, 
corundum, andalusite, staurolite, quartz, and pyrite, and are thought 
to have been originall}^ a highly aluminous shale. 
«Vei-hancll. geol. Reichsanstalt, Wien, No. 8, 1888, p. 178; Am. Naturalist, 1889, p. 524 
(Abst.). 
" Sitzungsber. K. Akad. Wiss., Wien, vol. 87, 1883, p. 358. 
<^ Sitzungsber. Niederrhein. Gesell., Bonn, May 7, 1888. 
'^ System of Mineralogy, 6th ed., 1895, p. 212. 
« Sur les enclaves acides des roches volcaniques de I'Auvergne : Bull. See. mineral. 
France, No. 15, 1890, pp. 100-106; Am. Naturalist, 1891. p. 110 (Abst.) ; Mem. Acad. 
Sci., Paris, vol. 31 ; Am. Naturalist, 1895, p. G57 (Abst.). 
fUin. und petr. Mittbeil., vol. 14, 1894, p. 17; Am. Naturalist, 1894, pp. 946-947 
(Abst.). 
» Geol. Mag., vol. 3, 189G, pp. 492-494. 
" Bull. Soc. geol. France, vol. 14, 1886, p. 888. 
