222 The American Geologist. April, 1892 
out of natural mineralized water in some of. the mines or caverns 
there. Certain forms of gypsum too, have been known to form 
within a few years, and I am here reminded of the fact of a man 
being lost in the great Dalecarlian copper mines, at Falun in 
Sweden, in the last century, whose body when discovered, was 
partially converted into a yellowish gypseous mineral, it having, 
as is supposed, fallen into or become covered with mine-water. 
Stalagmite, sinter, tufa, etc., do form quickly, as in the vicinity of 
hot springs, ‘‘petrifying wells,” in caves, in old mines, ete. 
(Juite hard and thick deposits of lime, iron, ete., are frequently 
found in mine water-pipes, cisterns, in old ‘‘atmospheric engines, ”’ 
and other places where conditions favor their deposition; however 
the writer cannot call to mind an actual case of hard pure iron 
ore proved to have formed within ancient or modern history, 
unless certain curiosities taken occasionally from blast furnaces 
(results of peculiar melting and deposition in connection with 
other mineral substances) may be regarded as such, or the instance 
quoted by Bischof in his ‘‘Chemical and Physical Geology” of 
three feet thick of limonite occurring over a substance containing 
{oman coins, in central Kurope. Swedish ‘‘bog iron-ore”’ is 
stated to form at the rate of several inches in a few years. The 
writer remembers a very singular case of rapid growth of a spec- 
imen from a coal mine in Staffordshire, England. It was placed 
ina cabinet and being left to itself for twenty-five years, was at 
the end of that time found to have eaten its way upwards through 
one inch of wood (the top of the cabinet, ) and downwards through 
three earthenware plates on which it was placed. Its owner stated 
that its growth in bulk had since been so extensive he had broken 
off fragments, to keep it within bounds, to the extent of five or 
six times its original bulk. Scientists who had examined this 
specimen consider it to be a variety of copiapite, or ? coquimbite 
Alunogen or *‘hair-salt,” or ? ferrous sulphate is another mineral 
of rapid growth in favorable situations; the writer measured some 
fibres in an entry in an English coal mine, in May, 1880, which 
entry had to his own knowledge been driven about eight years. 
The longest fibres were 11} inches, thus giving an average annual 
growth of nearly 15 inches. Other facts might be cited, but 
enough has been said here to show that whether fibrous hematite 
can orcannot form rapidly under favorable conditions, many min- 
erals or combination of minerals can and do grow amazingly fast. 
Additional specimens of this lake Superior ore, could they be 
