J. J. Harris Teall—On Hypersthene Andesite. O47 
I quote the following analyses for comparison with the above :— 
Il II. Vii. 
SiO, Root easnn ts Ol eO ,  Aoe esse Or 04 Sin re Neem RROnO rate 
Ab) OU aa ee Oh ailvatites) eee 2906/0. mys noe 
Fe.03 506 metal — 904 605 ——e eos ale 1°60 
FeO CO Ne 23 Ne ia Meeps ue 7/ ESS Vn nore we CNR OO) 
MnO ceo) cod eo 2 Mie canmtics Oe Oe cesn cae tt 
CaO BOAT ee oF OOS trace naene DUO es dhe diese) 
MgO Reel see V2 OLs) | Looks eos OL Mita weed ple Oo 
Na,O Be Nee — soe Gees Caer aso ae | ROT 
98°72 99-595 99-64 
I. Hypersthene, St. Paul’s (Damour). Quoted from Dana’s Mineralogy, 1868, 
p- 210. 
Il. Hypersthene from the hypersthene andesite of Buffalo Peaks (Hillebrand). 
Bulletin of the U.S. Geological Survey, No. 1, p. 29. 
III. Hypersthene from Santorin lava of 1866 (Fouqué). Quoted from the above- 
mentioned Bulletin. 
The predominating Cheviot pyroxene is therefore without doubt 
hypersthene. 
The analysis of the Steinerne Mann pyroxene is chiefly remark- 
able on account of the large per-centage of lime, but it is worthy 
of note that in this respect it does not differ markedly from the 
Santorin hypersthene of M. Fouqué. From the microscopic ex- 
amination of thin slices of the rocks, and also of the material 
isolated by hydrofluoric acid, I cannot think that this high per- 
centage of lime is to be accounted for by supposing an admixture of 
hypersthene and augite in the material submitted to analysis. I 
incline, therefore, to the view that lime enters more largely into the 
composition of some of these rocks forming hypersthenes, than the 
older analyses of this mineral would lead one to expect. This, after 
all, need not occasion surprise when we consider the intimate rela- 
tions subsisting between CaO, MgO, and FeO. 
Itake the opportunity which this paper affords of calling attention 
to several other rocks in which I have observed the rhombic pyroxene. 
(1). A black rock labelled Propylite, Kremnitz, by Herr Stiirtz, of 
Bonn. Macroscopically and microscopically this rock resembles very 
closely the two rocks to which special attention has been called in 
this paper. Glassy felspars (Mikrolin) and some small pyroxenes 
lie scattered throughout a compact ground-mass. 
(2). A purplish-grey rock composed of white felspars in a compact 
matrix, labelled Pyroxen-andesit, Doluy Turcek, Kremnitz, by Herr 
Stiirtz. 
(3). A rock similar to the above, labelled Pyroxene andesite, 
Lokajen Berg, Ungarn, by Herr Stirtz. 
_ These last two rocks have a ground-mass full of colourless felspar 
microlites, and therefore remind one very much of some of the less- 
altered Cheviot porphyrites. The rhombic pyroxene occurs also in 
slides of the following Hungarian rocks supplied by Messrs. Voigt 
and Hochgesang :—(1) Grey trachyte (Richthofen), Gonezerthal, 
Gonez, 8. Ujvas, Albanier Com. (2) Grey trachyte, Ober Kemenecze, 
Albanier Com. (8) Grey trachyte, Magos Tér, 8. Telki Banya, H.S.E. 
