1090 `- The American Naturalist. [December, 
Though the parallel growths of augite and hornblende, with the lat- 
ter mineral surrounding the former, are common, the reversed phenom- 
enon is rare. Hobbs," however, has recently pictured an example of 
light green amphibole completely encircled by colorless augite from an 
augite-hornblende rock occurring at New Marlboro, Mass. 
Analyses of American Minerals.—Several analyses of dode- 
cahedral crystals of aguilarite from Guanajuato, Mexico, have been 
made by Genth and Penfield." That from the purest material gave: 
Ag = 84.40 %; Cu= 49 4; 8 —11.36 % ; Se (diff) — 3.75 %. The 
mineral is thus an argentite with an eighth of its S replaced by Se. 
Metacinnabarite particles disseminated through barite from San Joa- 
quin, Orange Co., Cal., gave the same authors: Hg = 85.89 75 ; S= 
13.69 75; C1 — .82 %. The mineral supposed to be leucopyrite," from 
Meeker Co., N. C., is lollingite, whose composition is Fe — 70.83; 
Cu — tr; As — 27.93 %; S= 77%. Rutile crystals with the habit 
of cassiterite are found i the quartz decomposition products of the 
orthoclase from West Cheyenne Cañon, El Paso Co., Col. They are 
iron black with a density of 4.249, and the composition: SnO, = 1.40; 
TiO, = 91.96; Fe,O; — 6.68. The quartz decomposition products re- 
ferred to yield, upon analysis: 
SiO, ALO, FeO; NaO K,O Los Total 
96.63  .93 .85 o 46 95 = 9902 
Pieces of a large danalite crystal from the same locality, give: 
SiO, BeO CuO ZnO FeO MnO S. Loss Total—O 
30.26 12.70 .30 46.20 6.81 1.22 5.49 .21 100.41 
The danalite is associated with quartz, astrophyllite and a new yttrium 
. calcium fluoride with a hardness of 4 and a density of 4.316. Its com- 
position is: CaO = 19.41; (Yt Er) ,O, — 47.58, etc. The other miner- 
als whose analyses are recorded by the authors, are: altered zircon 
(eyrtolite) from Mt. Antero, Col. ; lepidolite, from Tanagama Yama, 
apan, and fuchsite, from Hahestas Co. Ga. The analyses of the. 
lepidolite and fuchsite follow : 
w Sci., Dec. 28, 1892, p- 
u Amer. Jour- Sci., Nov., 1892, p: 381. 
2 Bull. U. S. Geol. Survey, No. 74, p. 26. 
