Sentence:  <WSD>Aventurin</WSD> is also the name of a variety of quartz spangled with mica or other shiny mineral. A variety of spangled feldspar, found especially in Russia, and when polished used as a gem and highly prized, is also called <WSD>Aventurin</WSD> or popularly "sunstone". 
Meaning of the word marked with <WSD> tags:  A variety of translucent quartz, spangled throughout with scales of yellow mica.