Rock-crystal sentence example
Obsidian and rock crystal were also used for knife making.
The intention would seem to have been to imitate vessels of rock crystal.
They are made usually of crown glass or rock crystal ("pebbles"), the latter being somewhat lighter and cooler to wear.
He fell upon a most ingenious plan of doubling the amount of double refraction of a prism by using two prisms of rock-crystal, so cut out of the solid as to give each the same quantity of double refraction, and yet to double the quantity in the effect produced.
There appears, however, to be some objection to the use of iridio-platinum for weights, as, owing to its great density (Î”=21.57), the slightest abrasion will make an appreciable difference in a weight; sometimes, therefore, quartz or rock-crystal is used; but to this also there is some objection, as owing to its low density (Î”=2.65) there is a large exposed surface of the mass.Advertisement
Air, flint, glass, rock-crystal, calcareous spar were examined, but without effect.
It is contained in a rock-crystal shrine, encased in silver, and is vested in full pontifical robes blazing with jewels.
Besides copper, according to Strabo, the island produced considerable quantities of silver; and Pliny records it as producing various kinds of precious stones, among which he mentions diamonds and emeralds, but these were doubtless nothing more than rock crystal and beryl.
The various forms of silica have attracted attention from the earliest times, and the water-clear crystallized variety was known to the Greeks as KOo-raXXos (clear ice), being supposed by them to have been formed from water by the intense cold of the Alps; hence the name "crystal," or more commonly rock-crystal, applied to this variety.
Clear transparent rock-crystal is used for optical purposes and spectacle lenses.Advertisement
A few magnificent specimens of rock-crystal twinned according to this law have been found at La Gardette in Isere, and in Japan they are somewhat abundant.
Further, these varieties may be of almost any colour, whereas transparent crystals have only a limited range of colour, being either colourless (rock-crystal), violet (amethyst), brown (smoky quartz) or yellow (citrine).
There appears, however, to be some objection to the use of iridio-platinum for weights, as, owing to its great density (ÃŽâ€=21.57), the slightest abrasion will make an appreciable difference in a weight; sometimes, therefore, quartz or rock-crystal is used; but to this also there is some objection, as owing to its low density (ÃŽâ€=2.65) there is a large exposed surface of the mass.
April - Ever-popular diamonds are the stones for those born in April, with rock crystal serving as an alternate.