450

DESCRIPTIVE MINERALOGY.

SORDAWAL1TE.

Nordenskiiild’s Bidrag, p. 86.

567. Massive ; no traces of cleavage apparent.

H.=25—3. G.=2 53—2'58. Lustre vitreous. Streak liver-brown. Color gray-ish or bluish-black. Opaque. Fracture conchoidal. Brittle.

It contains, according to Nordenskiold , Silica 49 4, Alumina 138, Peroxyd ofIron 18-17, Magnesia 10 67, Phosphoric Acid 2-68, Water 4'38=98'02. Before theblowpipe, alone, it is difficultly fusible into a blackish globule. With borax it formsa green glass. With a small quantity of soda it fuses into a blackish-green glass;with a larger quantity into a slag. It is partly soluble in muriatic acid. It becomesreddish on exposure to the atmosphere.

Obs. Forms thin layers on common trap, near the town of Sordawala, in Finland ;at Bodenmais , in Bavaria , it is associated with magnetic pyrites. It resembles pit-coal in appearance. Nordenskiold first described and analyzed it.

TERENITE.

Emmons , Communication relative to a Geolog . Survey of New York , 1837.

568. Cleavage parallel to the sides and diagonals of a right square prism.

H.=2. G.=2 53. Lustre faint, pearly. Color yellowish-white, or pale yellowish-green. Fragile.

In the exterior flame of the blowpipe it is immediately converted into a white en-amel ; in the interior it fuses with ebullition into a porous glass. With nitrate of cobaltthe enamel assumes a lively blue color.

Oes. It occurs in a vein about an inch wide, traversing granular carbonate oflime, in Antwerp , St. Lawrence Co., N. Y. Its name alludes to its characteristicfragility, and is derived from the Greek rcpijr, tender.

TRIPOLI.

569. A mechanical mixture of sand and clay ; according to Bucholz and Haase,it contains

Silica

810

90

Alumina

1-5

7

Oxyd of Iron

80

3

Sulphuric Acid

3-5

—

Water

5 0=99, B.

—

It occurs massive, of a yellowish-gray color , a meagre, and somewhat rough feel,but does not adhere to the tongue. It imbibes water, by w-hich it is softened. Whenburnt, it becomes quite hard. It occurs near Prague , in Bohemia ; in diluvial bedsat Auberg, in Bavaria , and many other places. It is used in polishing metallic sur-faces, and occasionally in making forms for casting.

WEBSTERITE.

Aluminite. Hallite. Trisulphate of Alumina, Thom.

570. Reniform, massive ; impalpable.

H.=1'5—2. Yields to the nail. G.=1'6606. Lustre dull, earthy. Streak white,a little glimmering. Color white. Opaque. Fracture earthy. Adheres to thetongue, and is meagre to the touch.

It, contains, according to Stromeyer, (Untersuchungen, p. 99.)