468 Scientific Intelligence. 



origin is a novel phenomenon of great interest, the author has 

 studied with care the field relations of the rock mass. There is, 

 however, no direct evidence to be obtained from the exposures as 

 to its intrusive nature. So far as can be made out, it occurs as 

 lenticular masses in the schists. There are many points, how- 

 ever, to be seen in the field which are characteristic of igneous 

 masses, and balancing all the evidence obtainable the writer feels 

 it to be distinctly in favor of considering the rock masses erup- 

 tive in origin. The foliated structure is thought to have been 

 imposed before complete consolidation. Agreeing with this 

 view, we are now forced to recognize graphite as a new and pos- 

 sible constituent of igneous rocks, which may give rise to new 

 types on occasion. 



The corundum occurs in a feldspathic rock associated with the 

 eleolite-syenite. Some varieties contain a red garnet, others 

 chrysoberyl. This syenite is found with the eleolite-syenite in 

 such a way that its exact relations cannot be definitely told, but 

 it is held to be a differentiated product of the same magma. 

 There is thus a remarkable analogy with the occurrence in 

 Hastings County, Ontario.* l. v. p. 



1 1 . On a Peculiar Form of altered Peridotite ; by T. H. 

 Holland. Mem. Geol. Surv. India, vol. xxxiv, pt. 1, pp. l-9 r 

 1901. — The auther describes a rock mass at Huliyar, Mysore 

 State, India, consisting of a matrix of interlaced colorless talc 

 and pale green picrolite (columnar serpentine) with numerous 

 granules of a rhombohedral carbonate and magnetite dust in 

 which lie well-formed, porphyritic crystals of dark gray breun- 

 nerite, from one-half to one inch across ; they form 35 per cent 

 of the rock. From its staining with iron oxide the rock appears 

 like a diabase with porphyritic pyroxenes or hornblendes. The 

 matrix and breunnerites were analyzed separately, and combining 

 the analyses the rock is found to have the composition 



• Si0 2 Fe 3 4 MgO 0O 9 H 2 



27'3 12-7 35-0 20-0 5'0 — lOO'O 



From this it is assumed that the rock was a dunite which has 

 been changed by the action of water and carbonic acid. l. v. p. 



12. Perknite. — This name has been proposed by H. W. Turner 

 for the dark-colored, heavy, basic, noncrystalline igneous rocks 

 composed of monoclinic amphibole or pyroxene or both. In 

 addition to these chief components, rhombic pyroxene, olivine or 

 feldspar may occur as secondary ones and there maybe accessory 

 biotite, iron ore, etc. These rocks have hitherto been called 

 pyroxenite or amphibolite or hornblendite, but they have not 



*The occurrence of graphite as a well-marked constituent of an igneous rock 

 is a matter of great interest and importance. It will be correlated with the 

 diamonds in the peridotite.s of South Africa and m certain meteorites and throws 

 new liyht on its occurrence in pegmatite dikes described from Canada. If it can 

 be definitely shown by sufficient evidence that carbon is a constituent of the 

 deep-seated magmas, certain vexed questions in geology may be susceptible of 

 a better explanation than any yet offered, l. v. p. 



