Volltext Seite (XML)
328 ZEOLITE FAMILY. 7. Laumonite. Lomonit, Werner. Zeolithe efflorescente, Ilauy, t. iv. p. 410.—Lomonit, Ham. s. 95, Id. Karsten, Tabel. s. 32.—Laumonite, Hauy, Tabl. p. 49- Id. Lucas, t. ii. p. 188. Id. Steffens, b. i. s. 409- Id. Hoff. b. ii. s. 267. Id. Lem, b. i. s. 470.—Spathigcr Dolo- mit, Oken, b. i s. 393. External Characters. Its colours are yellowish-white, snow-white, and grey- sh-white. It occurs massive, and sometimes crystallised, in slight ly obliqqe four-sided prisms, in which the lateral edges are rounded off, so that the crystals acquire a reed-like as pect, and are bevelled 011 the extremities, the bevelling planes set on the obtuser lateral edges. The crystals are small, superimposed, and form druses. Internally it is sometimes shining, sometimes glisten ing, and the lustre is pearly. The fracture is foliated, with a twofold cleavage; and the folia are delicately longitudinally streaked. The fragments are angular and blunt-edged. It occurs in distinct concretions, which are large and small longish granular. When in a fresh state it is transparent, but on expo sure to the atmosphere, it very soon becomes opaque. It is so hard as to scratch glass when fresh; but on exposure to the atmosphere, it soon becomes so soft as to yield to the mere pressure of the finger. Is uncommonly easily frangible ; and Rather heavy, approaching to light. Specific gravity, 2.234', Bournon. Chemicdt