1830 .] 
47 
and Mineralogical Observations . 
Rock salt requires no description ; its form of crystallization is the cube into 
which it is generally cleavable. 
Coal. There are three kinds of coal ; namely, anthracite, bituminous coal, and 
lignite or wood coal. 
Anthracite is found in the primitive series; it is without bitumen, and, therefore, 
chemically, is nearly the same as charcoal or coke, or the diamond. Seams of an- 
thracite are also sometimes found in the coal formation, that is, along with beds of 
bituminous coal. 
Graphite or Plumbago maybe considered a variety of anthracite, hut it generally 
contains also iron. The beds of bituminous coal in that part immediately in con- 
tact with whin dykes, are frequently without their bitumen ; hence in this portion 
like anthracite. 
Bituminous coal is the coal of the great and useful coal of formation ; it never 
contains in itself vegetable impressions or immediate indication of a vegetable origin ; 
it is, however, considered by many geologists, to he derived from vegetable matter. 
There are, however, in the beds which accompany it, as the bituminous schale, 
many vegetable remains, as reeds, palms, &c. &.c. 
The beds which always accompany the bituminous coal, and hence termed the 
coal formation or coal measures, are chiefly sandstones, but also slate clay, clays, 
shales, and in some of the formations, beds of limestone ; but the latter are not 
found in the Newcastle beds. In the slate clays are found the ironstone in nodules 
containing about 33 per cent, oxide of iron : it is from this ore that the furnaces of 
England are supplied, limestone being used as a flux, and in some places basalt, 
which besides its easy fusion has the advantage of containing a portion of iron. 
The beds of sandstone in the coal formation, generally contain a portion of mica, 
and have an argillaceous cement ; they are commonly white, and have black spots of 
coaly matter. These sandstone beds arc often worked for a building stone, termed 
freestone, and when the portion of quartz is large, for millstones, then called mill- 
stone grit. When the proportion of mica is large, these sandstones are sometimes 
used for furnaces, and termed fre-stone. 
Lignite, or wood coal, is found much higher in the series than the bituminous 
coal, being found in the oolite, and beds still higher, (see fig. 6 and 7.) It is ge- 
nerally brown, or even, when black, the powder from it is brown ; it bears evidence 
of having been formed by vegetable matter, since the fibres of the trees can be 
traced in it. It is sometimes worked in the Continent, but scarcely ever in this 
country, and then only for factories, being disagreeable for domestic use ; the seams 
are also generally thin. The finding of this coal, as must be evident from its po- 
sition in the series, gives no indication of being in the neighbourhood of the great 
coal formation, but the contrary. 
Jet is a lignite highly biturninized. 
Cannel coal is nearly the same as Jet ; it is said to have its name from the word 
candle, as being used to give light. 
Petroleum, naphtha, mineral pitch and oil, found in various parts of the 
world, in pits and wells, are considered, in some cases, as being derived from tint 
coal ; in others, the derivation is not at all established. 
Of ores, iron, and copfer pyrites, lead glance, and the various ores of iron, 
are the most likely to be met with. Some of the latter are, however, often in a state in 
which they cannot be determined by their external character, being mixed with earth, 
or in a state of decomposition. The bog and meadow iron are found in masses or 
lumps on the surface, and are supposed to be formed by deposition from water, hav- 
ing iron in solution. This ore is, in many situations, used to a considerable extent, 
and affords a good metal. For the character distinguishing iron and copper pyrites 
from each other, and also the various ores which may occasionally he met with, 
reference must be had to works on mineralogy. 
It will be seen from the preceding descriptions, that it is chiefly the crystalline 
rocks which are distinguished by their mineralogical composition : these lie lowest 
in the senes, and in following it from them to the upper beds, the general charac- 
ter is, their becoming less distinct and crystalline, or more mixed and earthy as we 
ascend. This has led to divisions in the series ; and although the names thus given 
are dependent on a theory or supposed order of formation, now almost abandoned, 
still the terms are retained by most geologists, as being understood from their hav- 
ing been so long established. 
The divisions alluded to are those introduced by the school of Werner, of primi- 
tive transition and secondary, which may be defined as follows : — 
