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Ch. 6: Opal

Ch. 6: Opal Page of 515 Ch. 6: Opal Text size:minus plus Restore normal size   Mail page  Print this page
LABRADOR.
317
to be hoped that we will shortly acquire skill, and exert sufficient industry to compete with foreign manufacturers in the art of making porcelain, with the superior material which nature has so abundantly lavished on this continent. I possess a splendid slab of the vitreous felspar, of one square foot, free from any admixture, and imposing in appearance.
LABRADOR
This mineral was heretofore considered as a variety of felspar; but it has latterly been separated from it, and ought, therefore, no more to be called labrador felspar, the name by which it is known in all mineralogical works.
Labrador was first discovered by the Moravian mission­aries on the island of St. Paul, on the coast of Labrador; and, according to others, by Bishop Launitz, in 1775, when it was first brought- to Europe. Labrador occurs in crystalline masses, massive, and in boulders; it is of an uneven and conchoidal fracture; its lustre is vitreous, and in one direction pearly; it is translucent; its colors are gray, with its various shades, such as blackish or whitish-gray, with spots of an opalescent or iridescent vivid play of colors, consisting of blue, red, green, brown, yellow, or orange, according to the direction in which light is falling upon the specimen ; sometimes several of these colors ar.e perceptible at the same instant, but more commonly they appear in succession as the mineral is turned towards the light. These colors are said to originate in fissures which intersect the texture of the mineral, as they are only per­ceptible from that side where they fall together with the foliated structure, and not like the opal, whose mass is sup­plied with fissures running in all directions.
Labrador scratches white glass, is' scratched by rock-crystal, and is somewhat less hard than felspar; its specific
Ch. 6: Opal Page of 515 Ch. 6: Opal
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