FOUNDING OF THE ROCK VARIETY LITCHFIELDITE. 2-13 



while the more basic members of this group of minerals are entirely 

 wanting. ( Jonsequently, in spite of the great predominance ofalbite over 

 orthoclase, we are quite justified in calling our rock an eleolite-syenite. 

 Its large percentage of albite, however, and its possession of but one bisili- 

 cate constituent^ and that a biotite (lepidomelane), seem to distinguish 

 it as a very well defined variety of eleolite-syenite, as well characterized 

 in the hand-specimen as in the thin section. Its peculiarities are so 

 strongly marked that the rock seems worthy Of a distinctive varietal 

 name, for which no more appropriate one can be found than litchfieldite, 

 derived from the familiar locality — Litchfield — whence nearly all the 

 specimens in the museums were obtained. 



Hawks' Hornblende-Syenite from Red Hill, Moultonboro, New 



Hampshire. 



Historical. — The New Hampshire rock was described by Hawes as a 

 hornblende-syenite in these words: 



"A beautiful variety comes from Red lull, in Moultonborough. It is composed 

 essentially of orthoclase, which exists in thin tabular twinned crystals, which 

 mostly lie in one plane, and consequently give to little specimens of the rock a 

 stratified appearance. The hornblende, which is irregularly distributed, is black, 

 but in thin sections it is deep yellow, and it incloses more or less biotite in its 

 mass. Microscopic -rains of blood-red hematite and black magnetite and crystals 

 of apatite are <lr ected, and by the aid of polarized light some plagioclase is found 

 to he present. < >nly a very Little quart/, is seen in some little angular corners made 

 by the melting of the straighl edges of the orthoclase crystals. Little, partially 

 crystallized grains of sphene are found, and some of the grains of hornblende are 

 shown by polarized lighl to consist of two parts in t win relationship. As there are 

 large accumulations of this rock, it is one of considerable importance." 



Nothing is said of the method of occurrence of the rock, though similar 

 ones are described as existing in dikes. 



Mr. .!. S. Diller, in his search for a typical syenite for the educational 

 series of the United Stales Geological Survey, examined specimens of 

 the Red hill rock sent him by Professor \V. <). Crosby, of the Massachu- 

 setts Institute of Technology, who obtained them in turn from a man 

 who was instructed to collect the material from Hawes' original ledges. 

 A few minute.-' survey of the specimen.-- revealed the presence of blue 

 sodalite, and a tiny piece treated with hydrochloric acid gelatinized 

 easily. Sections of the rock were then made and turned over to the 

 writer for investigation, the results of which are recorded in the present 

 article. That the material furnished by Professor Crosby represents 

 Hawes rock is shown by its comparison with a specimen in the National 

 Museum labeled in Hawes' own handwriting. 



