1894.] Mineralogy and Petrography. 57 
MINERALOGY AND PETROGRAPHY-' 
The Granite of Santa Lucia, California, and a New 
Rock Variety Carmeloite.—The Santa Lucia Mountains’ in the 
vicinity of Carmelo Bay, California, consist largely of a porphyritic 
granite whose phenocrysts of glassy orthoclase are corroded with inclu- 
sions of cloudy orthoclase, plagioclase, quartz, biotite, apatite and mus- 
covite, which substances also constitute the groundmass of the rock. 
The striking feature of the inclusions is that their different areas are 
not only uniformly orientated with respect to each other, but they are 
also definitely orientated with reference to their host. They lie in cer- 
tain definite planes within the phenocrysts, and their crystallographic 
axes are definitely arranged with respect to the axes of their hosts. 
The quartzes all lie with their vertical axes nearly perpendicular to the 
basal plane of the orthoclase, consequently in sections of the pheno- 
crysts cut parallel to the basal pinacoid every included quartz grain 
exhibits the axial figure. Another feature worthy of notice is the ten- 
dency of the inclusions to idiomorphic forms, whereas, the same miner- 
als in the rock’s groundmass are always allotriomorphic. The facts of 
the idiomorphism of the inclusions and their definite orientation sug- 
gest to Lawson that these and their hosts are of contemporaneous age. 
This view is strengthened by the observation that many inclusions on 
the edges of the phenocysts have grown out into the surrounding 
matrix, in which, as has already been noted, the components are 
the same as those occurring as inclusions, but are much larger than 
these, and are allotriomorphically developed. This granite is cut by 
dykes of fine-grained aplite. 
The rock to which the author has given the name Carmeloite, is a 
young volcanic, marked by all the characters of a recent lava. Itis 
probably younger than the Monterey series of the Miocene, and older 
than the newer terrace formations of the region. Under the micro- 
scope the rock is seen to consist of phenocrysts of iddingsite, plagioclase 
and often augite in a matrix composed of a felt of small, lath-shaped 
plagioclase and granules of magnetite and pyroxene, lying in a glass 
containing numerons feebly polarizing globulites. There are six areas 
of the rock in the Carmelo Bay district, the occurrences differing 
mainly in the quantity of glass present, the presence or absence of 
1 Edited by Dr. W. S. Bayley, Colby University, Waterville, Me. 
2 A. C. Lawson, Bull. Dept. Geol. Univ. of Cal., Vol. I, p. 1. 
