DIATOM  ACEO  UK    DEPOSITS    IN    CALIFORNIA. 
447 
The  following  table  is  taken  from  the  Mineral  Resources  of  the 
United  States  for  1905,  published  by  the  United  States  Geological 
Survey : 
Production  of  infusorial  earth  in  the  United  States  from  1880  to  1905. 
Year. 
Quantity 
in  short 
tons. 
Value. 
Year. 
Quantity 
in  short 
tons. 
Value. 
1880 
1,833 
1,000 
1,000 
1,000 
1,000 
1,000 
1,200 
3,000 
1,500 
3,466 
2,532 
$45, 660 
10, 000 
8,000 
5,000 
5,000 
5,000 
6,000 
15,000 
7,500 
23,372 
50, 240 
21,988 
43, 655 
-1893 
$22,582 
1881 
1894 
2,584 
4, 954 
3,846 
3,833 
2,733 
3,302 
3,615 
4,020 
5,665 
9,219 
6,274 
10,977 
LI,  718 
1882 
1895 
20, 514 
26, 792 
22,385 
16, 691 
25, 302 
24, 207 
52  950 
1883 
1896 
1884 
1885 
1897 
1898 
1886 
1887 
1899 
1900 
1901 
1902. 
1888 
1889 
53, 244 
76, 273 
44, 164 
64,637 
1890 
1891 '. 
1903 
1904 
1905 
1892 
COMPARISON   WITH   OCCURRENCES   ELSEWHERE. 
Infusorial  earth  occurs  at  widely  separated  points  in  other  parts  of 
the  world.  One  of  the  largest  and  commercially  best  developed 
deposits  is  in  northern  Germany,  where  there  are  beds  of  this  mate- 
rial varying  from  20  to  50  feet  in  thickness  from  which  the  earth  is 
quarried  extensively,  dried  and  prepared  for  market,  and  shipped  to 
all  parts  of  the  world.  There  is  a  famous  deposit  at  Richmond,  Va., 
but  considerable  clayey  material  is  mixed  in  with  the  deposit  of 
diatoms,  the  analysis  showing  70  per  cent  of  silica,  a  considerable 
quantity  of  alumina,  and  some  iron  oxide.  The  bed  attains  a  thick- 
ness of  40  feet  in  places  and  extends  many  miles.  Other  deposits 
over  30  feet  thick  occur  at  Bilin,  Bohemia,  and  in  Aberdeenshire, 
England.  It  can  be  readily  seen  that  the  quantity  of  infusorial 
earth  at  these  places  can  not  compare  with  the  vast  amount  to  be 
found  in  California. 
IMPORTS. 
Some  infusorial  earth  is  imported  into  the  United  States  every  year, 
being  classed  with  the  so-called  rotten  stone  widely  used  in  the  manu- 
facture of  polishing  substances.  In  past  years  the  value  of  the 
imports  of  tripoli  and  rotten  stone  has  approximated  closely  the  value 
of  the  tripoli  produced  in  this  country,  but  the  amount  of  the  imports 
is  declining  with  the  increase  in  home  production.  The  value  of  the 
imports  in  1902  was  $39,926;  in  1903,  $34,977;  in  1904,  $23,022,  and 
in  1905,  $18,986,  as  given  in  the  Mineral  Resources  reports  of  the 
United  States  Geological  Survey. 
