Geology and Mineralogy. 161 
Another spodumene erystal, prismatic in habit and 18™™ long, 
resembled in aspect crystals of certain varieties of pyroxene. The 
crystal was altered and the faces consequently were dull and gave 
poor measurements. The planes finally identified were 
a (100, #4), B(010, #2), (10), m(120, 7-2), &(230, 7-3), h (021, 2-2), ¢(241, 
—4-3), £ (131, 3-3), « (231, 2-3), w (321, 3-3), v (341, 4-4). 
Of these, k, &, w and v were new to the species. 
Rourity.—The beauty and brilliancy of the black rutiles is 
strongly emphasized by vom Rath. The most remarkable crystal 
was a combination of the planes: 7-2(100), Z(110), ¢-8(536), at20); 
2-4(410), 1-2(101), 1(111), 821(8-$); of these the prism @-2 is new. 
The crystal was a twin of the rare type figured by Miller in his 
Mineralogy, the twinning-plane being 3-2. 
TouRMALINE.—Three crystals examined were 14 to 16™™ in 
length and 7 to 10™™ through the prism. They showed the two 
prisms, and the terminating planes #(1011), —$(0112), —24 
(0112), —2 (0221), in one crystal the form —4F was prominent ; 
the planes 3- Wiles were also identified. 
XENoTIME.—A few remarks are made in regard to some crys- 
tals already described more fully by Mr. Hidden. The terminal 
angle of the pyramid was found to be 124° 28’ and 124° 30’. 
11. Notes on Aquamarine from Mount Antero, Colorado, by 
Rey. R. T. Cross. (Communicated.)—The aqua-marines forming 
the subject of this note were obtained two or three years ago on 
Mt. Antero, in Chaffee County, Colorado, by Mr. N. D. Wanamaker. 
He states that they were found in the decomposed granite of 
the Sawatch Range, Continental Divide, above timber line, and 
most of them near together in one pocket. I have deferred writ- 
ing this note in the hope of being able to visit the locality myself, 
but in this I have been disappointed. 
The color of the aqua-marines is bluish green. The two largest 
crystals found were three inches long and about half an inch in 
thickness. Of those now in my possession eight crystals have 
terminations, and a dozen others are tolerably clear but not ter- 
minated. The longest crystal is one and three-eighths inches in 
length and three-eighths of an inch in diameter. The lower third 
is translucent, the remainder transparent, with some flaws. ‘This 
crystal, like the others, is finely striated on the prism, but the 
basal plane is very smooth and brilliant. The next crystal is very 
nearly the same size, is clear through its whole length, but has 
only an imperfect termination. Another is three-fourths of an 
inch long, and on its termination shows the planes 2-2 quite large, 
and the planes 1 and 2 very small. The terminal edges of the 
prism of a number of the crystals are rounded; and some of them 
exhibit what appear to be slender longitudinal cavities running 
parallel to the prism, and probably due to striations on the origi- 
nal crystal now forming the core. This central part, or core, is 
often very distinct ; it is transparent, while the outside layer, 
looked at lengthwise, is opaque.. Sometimes the core projects at 
