Photomicrographs of Quartz

 Quartz grains containing tiny mineral  or fluid inclusions (arrowheads).  Quartz grains are generally  subangular to subrounded (XPL)

 Manhang Formation
 Gangreung coalfield

 Photo courtesy of C. Lim

 Deformation lamellae of quartz formed  by dislocation along specific  crystallographic plane. Such lamellae  are probably of pre-depositional  because of intraparticle deformation  (XPL)

 Manhang Formation
 Danyang coalfield

 Photo courtesy of C. Lim

 Quartz replaced by calcite(left) (XPL)

 Manhang Formation
 Cheongseon coalfield

 Photo courtesy of C. Lim 

 Semi-composite quartz (XPL)

 Manhang Formation
 Cheongseon coalfield

 Photo courtesy of C. Lim

 Polycrystalline quartz grain with  sutured crystal-crystal boundaries.  Such quartz is classified as a  "unstable" grain. This quartz is  sourced from low-grade metamorphic  rocks(Young, 1976). (XPL)

 Manhang Formation
 Danyang  coalfield

Photo courtesy of C. Lim

 Quartz grain showing crystal units  with polyhedral outlines, smooth  intercrystal boundaries, and triple  junctions of the boundaries meeting  120^o. This quartz is classified as a  "stable" grain, which means it was  ultimately derived from medium- to  high grade metamorphic rocks  (Young, 1976). (XPL)

 Manhang Formation
 Gangreung coalfield

 Photo courtesy of C. Lim

 Quartz grains with secondary  overgrowth. Quartz grains are  generally subangular to subrounded  (XPL)

 Manhang Formation
 Danyang coalfield

 Photo courtesy of C. Lim

 Various types of quartz grains (XPL)

 Jangseong Formation
 Samcheog coalfield

 Photo courtesy of C. Lim

 Quartz grains containing abundant  vacuoles (XPL)

 Hambaegsan Formation
 Samcheog coalfield

 Photo courtesy of C. Lim

 Various types of quartzs (XPL)

 Gohan Formation
 Samcheog coalfield

 Photo courtesy of C. Lim