Quartet

(kwor-tet',) or QUARTETTE. [From It. quartet to.] (Mus.) A four-part piece or composition intended either for voices or instruments; if the latter, they are generally stringed instruments; viz., one violoncello, two violins, and one viola.-(Pros.) A poetical stanza of 4 lines. Quarto, (kwor'to.) [Same der iv.] (Print, .) A size of a book made by twice folding a sheet, which then makes 4 leaves: - it is written in an abbreviated form 4to. Also a book so folded. Quartz, (kwortz.) (Min.) The name given to crystallized silica, SiO2. It occurs either in the ma ive form when it is milky white, or tinged with iron and in distinct crystals; the crystals are six-sided prisms with pyramidal summits; cleavage is very imperfect, and twins are of frequent occurrence. Hardne 7; sp. gr. 2.5 to 28; lustre vitreous; it is of all colors, from perfectly colorle to black, pa ing through shades of yellow, red, brown, green, blue, and black, owing to the presence of metallic oxides. When colorle and transparent, it is usually called rock crystal; when purple, amethyst; when rose - red, or pink, rose quartz; when light yellow, false topaz; when of a brownish smoky tint, smoky quartz or cairngorm; when leek-green and opaque, prase; when spangled throughout with yellow scales, aventurin quartz. Other varieties are known as chalcedony, jasper, siderite, flint, horn-stone, opal, . [s. 747]