1190 The American Naturalist. [December, 
30.75; Na,0=14.24; K,O=4.73. This corresponds to (NaK),Al, 
Si,O,,, which according to the Rammelsberg view is (NaK),Al,(SiO,), 
+(NaK),Al,(SiO,),. By doubling the formula it becomes a combina- 
tion of albite and an alkaline anorthite, with nearly the composition of 
anhydrous natrolite. The new mineral is, consequently, a very basic 
alkaline feldspar, related to albite as follows: Albite = R,ALSi,O, ; 
sigterite = R,AI,Si,O,, Quetedite, from the Salvador mine in 
Quetena, Chili, is a reddish-brown, translucent to opaque mineral, 
with a slightly waxy lustre. Its hardness is 3, and density 2.08-2.14. 
It occurs” massive, associated with copper vitriol, and in prismatic 
monoclinic or triclinic crystals in the latter mineral. Its analysis gave: 
Sistas PEO S40; MgO—5.92; H,0—34-01 
—Fe,S,0,+MgSO,+13H,0. 
Gordaite accompanies sideronatrite from Sierra Gorda, near Cara- 
coles, in Chili, as one of a number of thin coatings covering this 
mineral.” It is glassy, transparent, and forms short, broadly-tabular 
pieces and crystals, or fibrous masses of a white to light gray color. 
Its hardness is 2.5-3, and specfic gravity 2.61. The crystals are 
triclinic prisms with their lateral faces vertically striated. The mineral 
forms the end member of a series of hydrous iron-sodium sulphates, of 
which sideronatrite, with but a small proportion of sodium, is the 
other end member. The composition of gordaite (SO,—50.85; Fe, 
O,— 19.42 ; Na,0—22.36; H,0—7.33) corresponds to Fe,S,0,+3Na, 
SO, 4- 3H,0. —— Zumarugite, from Tarapaca, Chili, is described by 
Schultze!! as a massive, colorless, radiated mineral, with a hardness of 
2, and a density of 2.03. In composition it differs from soda alum 
in its percentage of water, as indicated by the formula Na,SO,+Al, 
(SO), 4- 12H,0. Ciplite is a phosilicate of calcium occurring in 
the chalk of Ciply, in France.!2 
General.—Up to the temperature of 570° guartz crystals expand 
rapidly, both parallel and perpendicular to the vertical axis, and at this 
temperature become fissured. Above this temperature quartz expands 
very slightly, in some cases even appearing to contract. Between 
560° and 580° sections perpendicular to c become my refractive. 
The double refraction increases rapidly below 570°, and above this 
10 Frenzel. Min. u. Petrog. Mittheil, 1890, XI., p. 217. 
u Verh. d. Ver. Santiago, 1889, Ref. Neues Jahrb. f. Min., etc, 1890, I., 258. 
12 Ortlier: Ann. Soc. géol. du Nord., XVI., 1888-89, p. 270. Ref. Bull. Soc. Franc. 
d. Min., 1890, XIII., p. 160. 
13 Le Chatelier. Bull. Soc. Franc. d. Min., 1890, p. 112. 
