title: Collector's Guide to Quartz and Other Silica Minerals (Schiffer Earth Science Monographs)
author:  Robert J. Lauf 
description: The author holds a Ph.D. in Metallurgical Engineering, and has conducted scientific research in fields ranging from nuclear fuel to microwave processing and biomineralization. He has been granted over 40 U.S. Patents, and has written 10 books on mineralogy for collectors.
zlib_text: SILICA, CRYSTALLINE (Respirable Size)*
  First Listed in the Sixth Annual Report on Carcinogens as Reasonably Anticipated to be a
  Human Carcinogen -- changed to Known to be a Human Carcinogen in the 
  Ninth Report on Carcinogens 
  CARCINOGENICITY
  Respirable crystalline silica (RCS), primarily quartz dusts occuring in industrial and 
  occupational settings, is known to be a human carcinogen, based on sufficient evidence of
  carcinogenicity from studies in humans indicating a causal relationship between exposure to
  RCS and increased lung cancer rates in workers exposed to crystalline silica dust (IARC 1997,
  Brown et al. 1997, Hnizdo et al. 1997). 
  Crystalline silica is an abundant and commonly found natural material.
  Hazardous
  human exposure to RCS, primarily quartz dusts, occurs mainly in industrial and occupational
  settings.
  Respirable quartz levels exceeding 0.1 mg/m3 are most frequently found in metal,
  nonmetal, and coal mines and mills; in granite quarrying and processing; in crushed ston