The  texture  of  the  different  sheets  varies  considerably,  but  the  first
quality  rock  runs  quite  uniformly.  It  always  shows  a  lamination
parallel  to  the  original  sheeting  and  should  therefore  be  laid  on  its
bed  in  structures.  The  quartz  and  feldspar  grains  are  of  approxi-
mately the  same  size  and  unite  with  the  small  mica  plates  to  form  a
uniformly  textured  rock  of  dark  gray  color.  The  different  beds  vary
somewhat  among  themselves  in  the  size  of  the  grain,  in  the  relative
amount  of  quartz  and  feldspar  and  in  the  amount  of  lamination.  As
is  true  of  many  sedimentary  gneisses,  this  difference  in  the  dark  and
light  bands  is  so  well  defined  that  the  quarrymen  by  a  little  sorting
may  furnish  material  which  will  run  uniformly  for  individual  ship-
ments. There  will,  however,  be  some  difference  between  different
shipments,  unless  considerable  care  is  exercised  by  the  quarry  master.
