334 
MINERALS. 
Both the masses and beds of minerals exhibit va- 
rieties in their formation : some appear to have 
been composed of crystals mixed together in a con- 
fused manner, and united without any apparent at- 
tention to figure ; such are the stones generally 
known by the name of granite, porphyry, statuary 
marble, &c. We observe that these stones are al- 
ways situated beneath every other, and that they 
never enclose any remains either of the animal or 
vegetable kingdom. 
Many layers are of a more homogeneous texture, 
and of a finer grain : they rather appear as if de- 
posited like a sediment, than formed by any at- 
tention to regularity in their structure. These 
beds, or layers, are always placed either mediately 
or immediately above the others, and frequently 
contain the remains of organized substances: among 
them may be noticed slate, lime-stone, plaster, and 
most of the coloured marbles. 
A third kind remains to be mentioned, which is 
supposed to derive its origin from the wreck of the 
first and second. This is found in the shape either 
of sand or pebbles ; and although it does not appear 
to have any determinate relative place, it is never- 
theless commonly found upon the surface of the two 
former. 
To these three kinds of earth may yet be added 
a fourth, which, in its nature, and certainly in its 
origin, is very different from the three preceding. 
This is daily formed in many parts of the world ; 
and being ejected from the bowels of burning 
