dale.  I  STATE    INVESTIGATIONS    DURING    1004.  487 
pany,  at  Northfield.  The  slate  is  closely  related  in  quality  to  the 
Brownville  slate  of  Maine,  but  is  without  the  considerable  percentage 
of  magnetite  which  makes  the  Brownville  slate  objectionable  for 
electrical  purposes.  It  contains  more  pyrite  and  a  very  small 
amount  of  carbonate.  Owing  to  the  absence1  of  flat  joints  and  rib- 
bons, it  has  to  be  channeled  across  the  cleavage,  and  works  up  more 
economically  as  mill  stock  than  as  roofing  slate,  although  it  is  very 
sonorous  and  has  a  line  cleavage.  This  new  company  is  conducting 
its  operations  with  more  deliberation  than  is  visual  in  slate  quarrying. 
A  trip  was  made  into  Virginia.  Certain  slate  prospects  5  and  6 
miles  southwest  of  Warrenton,  in  Fauquier  County,  which  had  been 
opened  long  before  the  civil  war  were  examined  and  were  found  to 
be  probably  of  little  more  than  local  value  owing  to  the  uncertain 
thickness  of  the  formation  at  that  point  and  the  abundance  of  pyrite. 
The  proximity  of  a  sulphur  spring  also  points  to  a  considerable 
amount  of  pyrite  in  the  slate. 
The  Arvonia  slate  district  in  Buckingham  Count}7,  in  the  same 
State,  was  next  visited.  Arvonia  slate  has  long  been  known,  for  it 
early  furnished  roofing  both  for  the  capitol  at  Richmond  and  for  the 
University  of  Virginia.  Although  this  slate  contains  a  small  amount 
of  carbonate  it  is  yet  so  crystalline  as  to  rank  among  the  better  class  of 
slates.  In  common  with  the  Maine  slate  it  contains  considerable  bio- 
tite.  An  important  result  obtained  here  was  the  determination  of  the 
recurrence  of  the  commercial  slate  beds  of  Arvonia  on  the  north  side 
of  the  James  River,  3|  miles  north-northeast  of  Arvonia,  in  Fluvanna 
County,  possibly  owing  to  a  slight  deflection  of  the  strike.  The  slate 
crops  out  on  the  estate  of  the  late  Dr.  Casey  Charles  Cocke,  '2  miles 
west-northwest  of  Bremo  Bluff.  Surface  prospects  show  a  crystal- 
line slate  of  finer  texture  and  lighter  color  and  less  carbonate  than 
that  of  Arvonia.  and  fully  warrant  expenditure  for  core  drilling  to 
penetrate  the  weathered  /one  and  test  the  fresh  slate  itself. 
Snowden,  in  the  Bine  Ridge,  in  Amherst  County,  was  next  visited. 
Although  the  deposit  is  extensive,  but  one  quarry  is  operated.  The 
attempt  to  use  this  slate  for  mill  stock  has  been  abandoned  and  it  is 
now  used  exclusively  for  roofing.  It  appears  to  have  less  carbonate 
than  the  Arvonia  slate,  but  to  be  less  crystalline. 
The  new  clay-slate  district  about  Martinsburg,  W.  Va.,  which  was 
briefly  described  in  Bulletin  213  (1902),  p.  363,  was  revisited  and 
some  new  outcrops  were  located.  At  the  only  quarry  opened — that 
of  the  Shenandoah  Slate  Company— the  manufacture  of  roofing  slate 
had  been  wisely  given  up  and  machinery  was  being  installed  for  mill 
stock,  for  which  the  material  is  better  adapted. 
Full  particulars  as  to  all  these  slate  deposits,  as  well  as  to  those  of 
Slatington,  Pa..  Hampton  and  Granville,  X.  V..  and  Pawlet-Poult- 
ney-Fair  Haven.  Vt.,  will  be  found  in  the  forthcoming  bulletin  on 
