32 THE CANADIAN NATURALIST. [Feb*. 



the head of diabase. The finer-grained and impalpable varieties 

 of diabase have received the name of aphanite ; which is often indis- 

 tinguishable from the corresponding forms of diorite, and like these 

 may become porphyritic, giving rise to the augite-porphyry of some 

 authors. Different varieties of this porphyry have received the 

 name of labradophyre, oligophyre, and albitophyre, according to 

 the composition of the imbedded feldspar crystals. These are 

 sometimes accompanied by crystals of augite, or are altogether 

 replaced by them. 



The name of hyperite or hypersthenite has been given to those 

 varieties of diabase which contain hypersthene or diallage. These 

 rocks occur abundantly in the Labrador series, where the hypers- 

 thene in them sometimes takes the form of a green diallage, or 

 passes into a finely granular pyroxene, and is associated with red 

 garnet, ilmenite, and a little brown mica ; in addition to which 

 epidote is said to occur in the hyperites of the same series in 

 New York, and olivine is mentioned as being found in the hyper- 

 ites of Sweden, and of the Island of Skye. Hornblende is also in 

 some localities associated with the hypersthene. The hyperites, 

 although indigenous rocks in the Labrador series in Canada, are 

 described as forming in other regions intrusive masses. 



Those varieties of diabase or hyperite which contain diallage,. 

 have, by the Italian lithologists been called granitone, but by 

 Rose and others have been described under the name of gabbro^ 

 This rock sometimes contains hornblende, mica, and an admixture 

 of epidote. A compact white or greenish- white epidote, or zoisite, 

 which has the hardness of quartz and a density of 3.3 to 3.4, is 

 the mineral named saussurite. This with smarao'dite, which is an 

 emerald-green pyroxene, often minged with hornblende, and 

 passing into diallage, forms the euphotide of Hauy. Com- 

 pact varieties of labradorite and of other triclinic feldspars have by 

 most of the modern litholoo-ists been confounded with saussurite, 

 and hence the name of euphotide is frequently given to the so- 

 called granitone or gabbro, which is only a diallagic variety of 

 diabase. The true euphotide often contains a portion of talc, and 

 sometimes encloses crystals of a triclinic feldspar, apparently lab- 

 radorite, thus offering a transition to diabase. See farther my 

 researches on euphotide and saussurite ; Silliman's Journal [2]^ 

 xxvii, 339, and xxxvii, 426. 



Under the name of dolerite, as already remarked, it is proposed 



