Sentence:  <WSD>Aventurine</WSD> is a variety of "grainy" quartz,—not quarts of rye whiskey, which there is too much of a venture in,—but quartz of silica, gold-spangled throughout with flakes of yellow mica. [...] There are two kinds of natural <WSD>aventurine</WSD>; the one with its spangles of yellow mica is well known as Muscovite talc. It was found on the shores of the White Sea in old times, and is now met with often in the mines of Silesia, in Bohemia, in France, and in Siberia. The other variety, more highly esteemed, is found in Spain and in Scotland. [...] Dealers have given the name of <WSD>aventurine</WSD> to a species of feldspar having the same external characteristics, and sold for the genuine, though a much softer stone. Such dealers are not honest. 
Meaning of the word marked with <WSD> tags:  A variety of translucent quartz, spangled throughout with scales of yellow mica.