203 
dull, opaque, pretty soft, mild, easily frangi- 
ble, adheres a little to the tongue, and feels 
meagre. It is genera:! found wherever the 
oval, lioetz trap, and alluvial iormatious oc- 
cur. 
Eleventh species. Poller, or Polishing- 
Stone, 
Is of a yellowish-grey colour, striped, and 
the colours alternate in layers. It occurs 
massive, is dull, very soft, adheres ta the 
tongue, feels tine but meagre, and is nearly 
swimming. It is found in the vicinity of 
pseudo-volcanoes, though hitherto ii has only 
been discovered in Bohemia. 
Twelfth species. Tripoli 
Is of a yellowish-grey colour, passing into 
ash-grey ; occurs massive, is internally dull, 
very soft, feels meagre and rough, does not 
adhere to the tongue, and. is rather light. It 
is found in veins and beds in lioetz rocks in 
Saxony, in Derbyshire, and many other 
countries besides Tripoli, from whence it was 
first brought. Its use in polishing metals and 
minerals is well known. 
Thirteenth species. Alum-Stone 
Is of a greyish-white colour, occurs mass- 
ive, shews a tendency to chrystallization, is 
soft, passing to friable, and light. It is found 
at Tolfa, near Rome, from whence the fa- 
mous Roman alum is manufactured. 
Fourteenth species. Alum Earth. 
The colour is a blackish-brown, and brown- 
ish-black ; it is massive, dull, feels a little 
meagre, and somewhat greasy ; is intermedi- 
ate between soft and friable, and light. It is 
found in beds of great magnitude in alluvial 
land, and in floetz trap formation in several 
arts of Germany, in Naples, and in France, 
t is lixiviated to obtain the alum it contains. 
Fifteenth species. Alum-Slate 
Is divided into two sub-species, as follow' : 
1. Common alum-slate is between a grey- 
ish and bluish-black colour, occurs massive, 
and in balls, is soft, not very brittle, easily 
frangible, and not very heavy, 
2. Glossy alum-slate is of an intermediate 
colour, between bltieish and iron-black ; oc- 
curs massive, with a shining semi-metallic 
lustre, and in other respects resembles the 
former. It is found in beds and strata in Sax- 
ony, France, Scotland, and Hungary ; and 
affords considerable quantities of alum. 
Sixteenth species. Bituminous Shale 
Is of a brownish-black colour, and occurs 
massive. Internally, its lustre is glimmering ; 
it is very soft, rather mild, feels rather greasy, 
is easily frangible, and not particularly 
heavy. 
It is found with clay- slate in the coal form- 
ation, in Bohemia, England, Scotland, and 
other coal countries. 
Seventeenth species. Drawing Slate, or 
Black Chalk. 
Its colour is a greyish-black, with a tinge 
of blue ; it occurs massive, is opaque, colours 
and writes, is soft, mild, easily frangible, feels 
meagre- but fine, and is rather light. 
It is found in primitive mountains in 
France, Germauy, Iceland, Scotland, and 
MINERALOGY, 
the Hebrides. When of a middling degree 
of hardness, it is used for drawing. 
Eighteenth species. Whet-Slate. 
1 lie common colour is greenish-grey ; it 
! s massive; internally, weakly glimmering,' 
semi-hard, feels rather greasy, and is not par- 
ticularly brittle or heavy, it occurs in pri- 
mitive mountains in Saxony, Bohemia, and 
the Levant. \\ hen cut and polished, it is 
used for sharpening knives and tools. 
Nineteenth species. Clay-Slate. 
Its principal colour is grey, of which there 
are many varieties. It occurs massive; in- 
ternally, its colour is glistening, the substance 
opaque, soft, pretty easily frangible. It is 
found in vast strata in primitive and transi- 
tion mountains in many different countries, 
but particularly in Scotland. When split 
into thin and firm tables, it is used tor rooting 
houses, and other purposes. 
Twentieth species. Lepidolite. 
Its colour is a kind of peach-blossom, red, 
verging on lilac-blue, and occurs massive, 
its internal lustre is glistening ; it is trans- 
lucent, soft, easily frangible, and easily melts 
before the blowpipe. Hitherto it has only 
been found in Moravia, where it lies in 
gneiss. 
Twenty-first species. Mica, or Glimmer. 
Its common colour is grey, of great va- 
riety of shades. It occurs massive, dissemi- 
nated in thin tables and layers in other stones, 
and chrystallized either in equilateral six- 
sided tables, or in six-sided prisms. The sur- 
face of the chrystals is splendent; internally, 
shining and splendent. In thin plates, it'is 
transparent ; but in larger masses only trans- 
lucent on the edges. It is semi-hard, feels 
smooth, but not greasy, elastically flexible, 
and more or less easily frangible. 
It forms one ot the constituent parts of 
granite, gneiss, and mica slate, and is almost 
peculiar to the primitive mountains. It was 
formerly used instead of glass, for windows 
and lanterns. Fig. 16.. 
Twenty-second species. Pot-Stone. 
Its colour is a greenish-grey, of different 
degrees of intensity; is massive; lustre, in- 
ternally, glistening and pearly, translucent 
on the edges ; soft, feels greasy, and is very 
difficultly frangible. 
It occurs in beds, oris indular ; and is found 
in the country of the Orisons, in Saxonv, and 
probably in Hudson’s-bay, and is nearly al- 
lied to indurated talc. 
Twenty-third species. Chlorite, 
Which see. 
Twenty-fourth species. Hornblende, 
Which see. See also fig. 17. 
Twenty-fifth species. Basalt. 
The usual colour is greyish-black, of vari- 
ous deg ees ot intensity. It occurs massive, 
in blunt and rolled pieces, and sometimes ve- 
sicular. Internally, it is commonly dull. It 
is usually found iu distinct concretions, which 
are generally columnar, and sometimes up- 
wards ot 100 feet in length. Commonly 
opaque, semi-hard, brittle, very difficultly 
frangible, melts without addition, and is al- 
most exclusively confined to the floetz trap, 
formation. It occurs in strata, beds, and ! 
veins, in almost every quarter of the globe, | 
and is very abundant in Scotland, Ireland, i 
and in ot tier, parts, of the British European ] 
dominions. It is useful for building, as a I 
touch- stone,, as a flux, and in glass manuiac- 1 
tures. 
Twenty-sixth species. Wacce. 
The colour is a greenish-grey, of various j 
degrees of intensity. It occurs "massive and 
vesicular, is dull, somewhat glimmering, 
opaque, usually soft, more or less easily! 
frangible, and- not particularly heavy. 
it is said to belong exclusively to the floetz’ 
trap formation, where it occurs in beds and 
above clay, and also in veins. It is found in' 
Saxony, Bohemia, and Sweden. 
Twenty-seventh species. Clink-Stone 
Is commonly of a dark greenish-grey eo- l 
lour, always massive, and occurring in irre- ; 
gu{ar columns, and tabular distinct concre-j 
tions. It is usually translucent on the edges, 
brittle, easily frangible, and when struck with 
a hammer, sounds like a piece of metal. 
It is said to belong to the floetz trap form- 1 
ation, and generally rests on basalt. It is 
found in Lusatia, Bohemia, South America, 
and in the isle oi Lam bash, in the frith of 
Clyde. 
Twenty-eighth species. Lena 
Is divided into two sub-species. 
1. Slag lava is of a greyish-black colour,-] 
passing into other shades. Externally, it isl 
spotted, occurs vesicular and knotty, is gene-1 
rally opaque, semi-hard, brittle, easily tan- 
gible, and not particularly heavy. 
2. ! oam lava is of a dark greenish-greyf 
colour, occurs small and fine, vesicular ; ex-j 
ternally, glimmering, slightly translucent on* 
the edges, brittle, easily frangible, and light.! 
It has often been confounded with pumice-1 
stone, from which, however, it differs very ] 
much. On account of its lightness, it is used 
with advantage in arching vaults, and other] 
kinds of building. 
Twenty-ninth species. Green Earth. 
Its colour is a celaden green, of various; 
degrees ot intensity. It occurs massive, in- 
angular and globular pieces, and also disse- 
minated. Internally, it is dull, streak glist-J 
ening, very soft, easily frangible, and light. 
It is principally found in amygdaloid, in 
Saxony, Bohemia, Scotland, ‘and other; 
places, and is used by painters. 
Thirtieth species. Lithomage 
Is divided into two sub-species. 
L triable lithomage, or rockmarrow, is 
snow-white, or yellowish-white, occurs mas- 
sive, as a crust, and disseminated ; is gene- 
rally coherent, feels greasy, and adheres to 
the tongue. Is found in tin veins, in Sax- 
ony. 
2. Indurated lithomage is most commonly 
white, of which it presents several varieties! 
is massive; internally, dull; streak sliming, 
very soft, easily frangible, feels greasy, and 
adheres strongly to the tongue. It occurs in 
veins of porphyry, &c. in Saxony, Bohemia. 
Bavaria, &c. 
Thirty-first species. Rock Soap 
Is ol a brownish or pitch-black colour^ 
