HANDBOOK FOR THE DEPARTMENT OF GEOLOGY. 563 



Mauy varietal names have been given from time to time by different 

 authors. Gumbel gave the name of leucophyr to a very chloritie dia- 

 base-like rock consisting of pale green augiteaud a saussurite-like pla- 

 gioclase. (Specimens 36439 and 36440, from Bavaria and the Vosges.) 

 The same authority gave the name epidiorite to an altered diabase rock 

 occurring in small dikes between the Cambrian and Silurian formations 

 in the Fichtelgebirge, and in which the augite had become changed to 

 hornblende. (Specimens 36370 and 70209, from Champ St. Veron, Bel- 

 gium.) He also designated by the term proterobase a Silurian diabase 

 consisting of a green or brown somewhat fibrous hornblende, reddish 

 augite, two varieties of plagioclase, chlorite, ilmenite, a little magnetite, 

 and usually a magnesiau mica. (Specimens 36435 to 36438, inclusive, 

 from Bavaria, Saxony, and the Vogesen.) The name ophite has been 

 used by Pallarson to designate an augite plagioclase eruptive rock 

 rich in hornblende and epidote and occurriug in the Pyreuees. The 

 researches of M.Levy Kuhn (Untersuchungen fiber pyreniiische Ophite, 

 Inaug. Dissertation) and others have, however, shown that both these 

 constituents are secondary, resulting from the augite alteration and 

 that the rock must be regarded as belougiug to the diabases. (Speci- 

 mens 36477 to 36480, from France.) 



The Swedish geologist Tornebohm gave the name sahlite diabase to a 

 class of diabasic rocks containing the pyroxene sahlite, and which oc- 

 curred in dykes cutting the granite, gneiss, and Cambrian sandstoues in 

 the province of Smaaland and in other localities. (Specimen 36441, from 

 Scotland). The name teschenite was for many years applied to a class 

 of rocks occurring in Moravia, and which, until the recent researches 

 of Bohrbach, were supposed to contain uepheline, but are now regarded 

 as merely varietal forms of diabase. (Specimens 36529, 36530, 36531, 

 aud 36533.) Variolite is a compact often spherulitic variety occurring 

 in some instances as marginal faciesof ordinary diabase. (Specimens 

 73124 and 73125, from the headwaters of the Durance, on the Franco- 

 Italian frontier.) The name eultrite or eucrite was first used by G. Rose 

 to designate a rock consisting of white anorthite and grayish green 

 augite occurring in the form of a dike cutting the carboniferous lime- 

 stone of Carliugford district, Ireland. These rocks were included by 

 Prof. Zirkell under the head of " anorthitgesteine." The name is 

 now little used, and rocks of this type are here included with the dia- 

 bases. (Specimens 35736 and 34828, from Fiumark, Norway.) 



The diabases are among the most abundant and widespread of our 

 so-called trap rocks occurring in the form of dikes, intrusive sheets and 

 bosses. They are especially characteristic of the Triassic formations 

 of the Eastern United States. 



The following are the principal varieties and localities now repre- 

 sented: 



Diabase : Near Calais, Maine, 70147 ; Waterville, New Hampshire (mica diabase), 

 27879; Ossipee, New Hampshire (labradorite porphyry), 27853; Medford, Massa- 

 chusetts, 26423; Hinghara, Massachusetts, 38377; Greenfield, Massachusetts, 



