﻿102 
  Thirtieth 
  Report 
  on 
  the 
  State 
  Museum. 
  

  

  Its 
  specific 
  gravity, 
  as 
  before 
  stated, 
  is 
  2.635. 
  Its 
  analysis 
  was 
  

   concluded, 
  before 
  the 
  importance 
  of 
  determining 
  the 
  percentage 
  

   of 
  titanic 
  acid 
  and 
  ferrous 
  oxide, 
  was 
  realized. 
  It 
  is 
  difficult 
  to 
  

   determine 
  from 
  the 
  results 
  of 
  the 
  analysis, 
  the 
  constitution 
  of 
  

   the 
  feldspar 
  present. 
  

  

  As 
  a 
  representative 
  of 
  the 
  intrusive 
  masses, 
  which 
  in 
  very 
  

   numerous 
  localities, 
  present 
  themselves 
  among 
  the 
  norian 
  

   rocks, 
  specimen 
  No. 
  21, 
  which 
  is 
  a 
  black-grey, 
  fine-grained 
  

   dolerite, 
  breaking 
  with 
  conchoidal 
  fracture, 
  was 
  analyzed. 
  Its 
  

   specific 
  gravity 
  in 
  mass 
  was 
  2.89, 
  in 
  powder 
  2.92. 
  An 
  analysis 
  

   was 
  made 
  upon 
  the 
  original 
  rock 
  I, 
  upon 
  the 
  portion 
  soluble 
  in 
  

   acid 
  II, 
  and 
  upon 
  the 
  insoluble 
  portion, 
  III. 
  

  

  

  Dolerite. 
  

  

  

  

  

  i. 
  

  

  n. 
  

  

  in. 
  

  

  Silica 
  

  

  43.41 
  

  

  

  43.410 
  

  

  Titanic 
  Acid 
  

  

  0.35 
  

  

  0.367 
  

   2.003 
  

   9.097 
  

  

  

  Carbonic 
  Acid 
  

  

  2.00 
  

  

  

  

  19.42 
  

  

  10.324 
  

  

  Ferric 
  Oxide 
  

  

  5.72 
  

  

  4.553 
  

   6.693 
  

  

  1.169 
  

  

  

  6.69 
  

  

  

  

  9.11 
  

  

  7.398 
  

  

  1.711 
  

  

  

  5.98 
  

  

  5.285 
  

  

  0.695 
  

  

  

  0.47 
  

  

  0.323 
  

  

  0.144 
  

  

  

  4.39 
  

  

  0.530 
  

  

  3.864 
  

  

  

  3.00 
  

  

  2.997 
  

  

  

  100.54 
  39.246 
  61.317 
  

  

  The 
  insoluble 
  portion, 
  by 
  direct 
  weighing, 
  amounted 
  to 
  60.78 
  

   p. 
  c. 
  Speculations 
  as 
  to 
  the 
  nature 
  of 
  its 
  mineral 
  constituents 
  

   will 
  be 
  found 
  in 
  Part 
  IV, 
  No. 
  21. 
  The 
  most 
  singular 
  fact 
  con- 
  

   cerning 
  it, 
  is 
  the 
  large 
  percentage 
  of 
  the 
  pyroxenic 
  ingredient, 
  

   which 
  appears 
  to 
  have 
  gone 
  into 
  the 
  acid 
  solution. 
  

  

  In 
  order 
  to 
  determine 
  the 
  nature 
  of 
  the 
  pyroxenic 
  portion 
  of 
  

   these 
  norian 
  norites, 
  two 
  minerals 
  were 
  selected 
  : 
  I, 
  Black, 
  with 
  

   sub-metallic 
  lustre, 
  breaking 
  into 
  cleavage 
  masses, 
  with 
  surfaces 
  

   an 
  inch 
  or 
  more 
  in 
  width, 
  occurring 
  in 
  seams 
  in 
  the 
  labradorite 
  

   of 
  Mt. 
  Marcy. 
  Specimen 
  analyzed 
  was 
  from 
  near 
  summit. 
  Its 
  

   microscopic 
  characters 
  are 
  given 
  under 
  Part 
  IV. 
  Sp. 
  Gr. 
  3.459. 
  

  

  