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XI. Account of a Discovery of native Minium. In a Letter 
from James Smithson, Esq. F. R. S. to the Right Hon. Sir 
Joseph Banks, K. B. P. R. S. 
Read April 24, 1806. 
MY DEAR SIR, 
I beg leave to acquaint you with a discovery which I have 
lately made, as it adds a new, and perhaps it may be thought 
an interesting, species to the ores of lead. I have found 
minium native in the earth. 
It is disseminated in small quantity, in the substance of a 
compact carbonate of zinc. 
Its appearance in general is that of a matter in a pulverulent 
state, but in places it shows to a lens a flaky and crystalline 
texture. 
< — 
Its colour is like that of factitious minium, a vivid red with 
a cast of yellow. 
Gently heated at the blowpipe it assumes a darker colour, 
but on cooling it returns to its original red. At a stronger 
heat it melts to litharge. On the charcoal it reduces to lead. 
In dilute white acid of nitre, it becomes of a coffee colour. 
On the addition of a little sugar, this brown calx dissolves, 
and produces a colourless solution. 
By putting it into marine acid with a little leaf gold, the 
gold is soon intirely dissolved. 
When it is inclosed in a small bottle with marine acid, and 
