Earths. 
M INEHALOGY. Earths. 469 
Found in the mountains of Swifierland, Carinthia, Hun¬ 
gary, Saxony, Sweden, and Italy. 
49. Granites montanus : compofed of mica, Ihorl, and 
garnets. 50. Granites virel'cens : compofed of mica, Ihorl, 
and amarus, or bitter earth. Found in the mountains of 
Swifierland. 
51. Granites radiatus : compofed of mica and adlinote. 
Found in the mountains of Swifierland, particularly St. 
Gothard. 
5 z. Granites olivinus: compofed of mica and olivin. 
53. Granites chlorofti&us : compofed of fhorl and olivine. 
54. Granites gemmaceus : compofed of garnets and oli¬ 
vin. Found in the neighbourhood of Vefuvius. 
55. Granites fimilaris: confiding of garnets and Ihorl. 
Found in the mountains of Swiilerland, and detached 
round Vefuvius, with fometimes a mixture of mica. 
56. Granites affinis: confiding of granatine and genu¬ 
ine diorl. Found in the neighbourhood of Vefuvius. 
57. Granites montium: confiding of garnets, diorl, and 
hornblende. Found in the mountains of Swifierland. 
58. Granites bradleatus : confiding of garnets and horn¬ 
blende. Found in the mountains of Swifierland. 
59. Granites argentatus: confiding of garnets, mica, 
and fpar. Found in the neighbourhood of Vefuvius. 
60. Granites lamellatus: confiding of mica and fpar. 
Found in the neighbourhood of Vefuvius. 
61. Granites lucidus: confiding of aftinote and fpar. 
Found in the neighbourhood of Vefuvius; and may pro¬ 
bably be an amygdalite. 
62. Granites albedinus: confiding of albedus and mar¬ 
ble. Found round Vefuvius; and is hardly of this genus. 
Gneissum.— Compofed of parts cohering together 
without any intermediate cement, often in the form of 
crydals, and fometimes alternating in layers, of a Jlaty 
(or rarely a fibrous) texture, forming plates laid on each 
other. Found in lofty primitive mountains, generally 
reding upon beds of granite : hard, not melting before 
the blowpipe, nor mouldering in the air. 
Gneifs is, like granite, eflentially compofed of quartz, 
felfpar, and mica; but its drufture is in the mafs fchif-- 
tofe, the feveral laminae being feparated from each other 
by thin drata of fcales or plates of mica; and, from the 
joint confideration of its compofition and firu&ure, it is 
occafionally called J'chijlofe granite, and granitic fchiftus. 
The done of which Mr. Smeaton built the Ed'dyfione 
light-houfe appears, by his defcription, to have been a 
fpecies of gneifs having a degree of eladicity. Gneifs ap¬ 
pears to be the mod ancient rock after granite, being ge¬ 
nerally placed immediately over it; and, according to 
Mr. Kir.wan, where gneifs is contiguous to granite, its 
quartz, and felfpar are more apparent; and the micace¬ 
ous part lefs predominant; where more didant from gra¬ 
nite, the contrary happens. Of all rocks, gneifs is the 
mod metalliferous ; and almod every metal has been 
found in this matrix. The mines of Saxony and Bohemia, 
and the filver-mines of Koniglberg in Norway, are in 
gneifs. Garnets are very often found in gneifs; and 
fometimes in very great quantity. There are thirty-one 
fpecies. 
1. Gneiflum fornacum, or common gneifs: confiding 
of the greater part quartz and mica. Found in molt 
mountainous countries of Europe, in innumerable va¬ 
rieties of proportion, combination, didribution, colour, 
and hardnefs ; and is chiefly covered with argillaceous 
flate, fand, and limedone. It is formed of diflintd plates 
laid on each other, and feparated by thin layers of mica; 
and is generally rich in metallic ores. It is ufed for lay¬ 
ing the beds of large melting-furnaces ; hence the trivial 
©r fpecific name, fornacum. 
2. GneiiTum micaceum, or micaceous fchiltus : quartz 
and mica are the eflentialiy-condituent parts of this rock ; 
the mica generally predominating confiderably. The 
fchidofe character of this is much more remarkable than 
that of common gneifs j but the one graduates into the 
Vol. XV. No. 1058. 
other almod imperceptibly. The laminae are fometimes 
remarkably contorted, as if fome force had been applied 
to them when in a foft date. Micaceous fchidus pafles 
infenfibly into the date in which it is called roofing -flute. 
It occurs in Norway, forming entire mountains, of a lil- 
very colour and fplendour; the plates of mica are ex¬ 
tremely thin and clofely compared together, fo as to 
form didinid tables ; the quartz is difpofed in fmall veins, 
granulations, or larger drata. 
3. GneiiTum alpinum, or alpine gneifs: confiding of 
quartz, mica, and garnets. Found in mod lofty alpine 
mountains of Europe. The mica is modly filvery, fome¬ 
times predominant, fometimes pretty equally didributed, 
fometimes hardly vifible. The garnets are more com¬ 
monly red than brown ; fometimes of a common form and 
of confiderable lize, fometimes crydallized and lefs : the 
plates of which it is compofed are frequently undulate. 
Sometimes there is found with it a portion of diorl, talc, 
or felfpar; when the quartz is in greater proportion, it 
is made into mill-dones. 
4. GneiiTum fcorlinum, or Ihorl-gneifs : confiding of 
quartz, mica, and fhorl. Found in the mountains of 
Swifierland, efpecially St. Gothard’s ; in thole of Hun¬ 
gary near Schemnitz; and containing veins of gold or 
filver; and in thofe of Bohemia, Saxony, and Norway. 
5. GneiiTum Altenbergenfe, or Altenberg gneils: con¬ 
fiding of quartz, mica, and lhorlite. Found near Alten¬ 
berg in Saxony ; having veins of tin within it. 
6. GneiiTum radians, or radiant gneifs : confiding of 
quartz, mica, and adfinote. Found in Jemtia in Sweden. 
7. GneiiTum Saxonum, or Saxon gneifs : confiding of 
quartz, mica, and felfpar. Found in the mountains of 
Saxony, Bohemia, Swifierland, and Silelia, rarely in the 
Carpathic mountains; in great varieties of proportion, 
colour, and condituent parts ; the mica is generally pre¬ 
dominant, and the felfpar the lead. 
8. GneiiTum Bornii, or argillaceous fchidus : confiding 
of quartz, mica, and alumine. Found in the metallic 
mountains of Hungary, Bohemia, Saxony, and Sweden ; 
and is often ufed as a whetdone to lharpen feythes and 
large indruments. Born's Ind. Fojj'. 
9. GneiiTum Jemticum, or Jemtian gneifs: confiding 
of quartz, mica, and deatite. Found in the higher moun¬ 
tains of Jemtia. It differs a little from others of its genus 
in gradually mouldering away when expofed to the at- 
mofphere. 
10. Gneiflum fpatofum, or fparry gneifs : confiding of 
quartz, diorl, and felfpar. Found near Halbendorf in 
Saxony. 
11. GneiiTum topafinum, topaz-gneifs : confiding of 
quartz, fhorl-, and topaz. Found at Schneekendein near 
Auerback in Voigtland. 
12. Gneiflum comeum, or hornblende Ihiflus : confid¬ 
ing of quartz and hornblende. Found at Portfoy in 
Scotland ; Saxony, Norway, and Sweden. Colour be¬ 
tween greenilh and raven black, and gives a greenilh-grey 
dreak. Texture radiate, and- breaking into indetermi¬ 
nate fragments ; is liardilh, and frequently found mixed 
with fmall particles of mica or garnets. 
13. Gneiflum argillofum, or clay-gneifs : confiding of 
quartz and alumine. Found in the Carpathian mountains. 
14. Gneiflum cotianun, or polilhing gnefs : confiding 
of alumine and mica- Found in Norway and Sweden ; 
hardilh, melting in the fire; and is uled by the inhabi¬ 
tants to polifli lteel indruments. Probably not of this 
genus. 
15. Gneiflum Aeatiticum, or fteatite-gneifs: confiding 
of deatite and mica. Found in the mountains of Nor¬ 
way, Sweden, Hungary, See. foft, and is ufed for the 
walls of melting-furnaces, and, when feparated into thin 
plates, for the covering of houfes. Probably not of this 
genus. 
16. GneiiTum graniticum : confiding of common diorl, 
garnets, and feilpar. 17. Gneiflum bicolor: confiding 
0 D C f 
