158 The American Geologist. September, i90i. 
Rocks composed largely of j^yroxene and containing' neither 
feldspar nor olivine have been mentioned by Hunt from Rouge- 
mcnt and Montarville, Canada;* by J. D. Dana and G. H. Will- 
iams fromi the Cortlandt series of New York ;t by Hutton from 
the Dun mountains in New Zealand ;$ by Turner from Mount 
Diablo, California, where the pyroxenyte is associated with 
peridotyte and gabbro ;§ and by Hatch from Madagascar.]! 
A word should perhaps be added concerning the usage of 
the term pyroxenyte. The name was first used by T. Sterry 
Hunt, who applied it both to intrusive rocks composed mostly 
of pyroxene, 1 1 and to nests of pyroxene in the Archean lime- 
stones of Canada and New York.** 
G. H. Williams in 1890 proposed that the term pyroxenyte 
be employed to designate those igneous rocks free from both 
feldspar and olivine and this is now the generally accepted 
usage. Pyroxenytes composed wholly or chiefly of hypers- 
thene, which are found at various localities in Cecil county, 
are of rare occurrence. Such a rock with very little diallage 
was found by Wiilfing in blocks on Monte Matterone, near 
Bavano, Italy, and Adams notes rocks of this variety contain- 
ing a little bytownite, from Shipsaw and Ha-Ha-Bay, Canada. 
At the latter locality the specimens carried some hornblende 
and olivine. ° So far as known these are the only localities out- 
side of Maryland where the hypersthenyte is found. 
The name hypersthenyte was first applied to rocks of the 
gabbro series composed chiefly of orthorhombic pyroxene and 
basic plagioclase and it is still sometimes employed in that 
sense. But the term noryte is now more commonly used for 
such rocks and hypersthenyte is reserved for those pyroxenytes 
composed largely of hypersthene. 
As already stated, these pyroxenytes are as a rule remark- 
ably fresh and unaltered. But along the serpentine border 
and elsewhere within the area smaragdite and other fibrous 
amphibole rocks are very common and these have in all prob- 
ability originated from the pyroxenyte. \Anien this alteration is 
*Geol. of Canada. 1873. p. 667. 
tAmer. .Tour. Sci., Srd Serio« Vol. XX, p. 1894, 1897. 
JTrans. Roy. Soc. New South Wales. 1889. p. 153. 
§Bul. Geol. Soc. Amer.. Vol. II. 1891, p. 383. 
HQuart. .Tour. Geol. Soc, Vol. XLV, 1889, p. 345. 
IIGeol. of Canada, 1863. n. 607. 
**CataIopue of the Canadian Rocks at the London Exhibition, 1862; and 
Geological Survey of Canada. Report for 1863-66. np. 185, 226. 
°Rosenbilsch, Mikroskopisrhe I'hysiographie, Vol. II, p. 361, 1896. 
