230 HAWATIAN ISLANDS. 
is indicated by a line of small cones extending down the slope on the 
southwest side, and near the base of the mountain, in the same line, 
by a stream of lava. This is the region where, according to the 
natives, an outbreak took place about two centuries since. 
The rocks of Hale-a-kala resemble those of Hawaii. The scoria and 
pitchstone cinders of the crater have been mentioned. ‘There are also 
the usual gray and black basaltic rocks or lavas; there are, besides, 
feldspathic rocks, allied to clinkstone, and resembling a similar rock on 
Mount Loa. Loose tabular crystals of a glassy feldspar were obtained 
in the crater, which were nearly transparent, and about half an inch 
in breadth. They prove, on analysis, to be a new mineral species, for 
which we propose the name 
Mauilite. Crystals tabular. Cleavage in one direction perfect, in a 
second less perfect; angle between the two 93° 15’. Specific gravity 
2-887. Hardness 6. ‘Transparent and colourless, with a highly 
vitreous lustre. Streak white. An analysis by Prof. Silliman, Jr., 
afforded— 
Silica, - - - : - 41°56 
Alumina, 2 : - - - 45:07 
Soda, - - - - - 12°74 
Magnesia, - - - - - 0°52 
which corresponds to the formula Al? Si + Na Si.* 
Dividing Plain or Isthmus.—The plain between the two mountains 
of Maui, in its lowest part, is but a few feet above the level of the sea 
at high tide. The breadth is about ten miles and the length fifteen. 
It slopes gradually, in some parts almost imperceptibly, into the accli- 
vities of Hale-a-kala, and is properly the foot of this mountain, uniting 
it to the western mountains. ‘The surface consists mostly of loose 
sand, with clayey or even marshy land in some portions. The sands 
are in part of coral origin, and appear as if of beach accumulation. 
The surface is arid, bearing scarcely any verdure. 
* « The crystals subjected to analysis weighed less thana gramme. 'They were finely 
pulverised with the aid of water, and ‘8036 gramme was decomposed by means of hydro- 
fluoric acid gas in a suitable apparatus of platinum. By this means, the silica was re- 
moved, and the whole was rendered soluble in dilute hydrochloric acid. The alumina 
was separated as usual, and the process of Berzelius was employed to separate the mag- 
nesia from the alkalies, i. e. by addition of oxyd of mercury and the dense solution of the 
mixed chlorids. The formula given requires the following proportions :—Silica, 40°78, 
Alumina, 45°41, Soda, 13°88, which rejects the magnesia as an unessential constituent.” 
—B. S., Jr. 
