EARTHS. SILICEOUS. 44. Feldfpatiim. 151 
In S-fided right angles. 
In 4-fided oblique angles. 
In 6-fided oblique angles. 
Found every where in primitive mountains, forming a part of 
Granite, Porphyry and Gneifs rocks, compafl, folid, and in- 
corporated with other fubliaiices ; and generally moulders 
into a kind of porcelane day ; colour generally fielh-colour,' 
blueiflt-grey, yellowifli-whitej milk-white or brovvnilh-yel- 
low, rarely blue or olive-green, very rarely black: texture 
in ftraight Ihining foliations, Crofs fraflure uneven : when 
heated, the cryllalliv.cd kind often decrcpidates : it is Icfs 
hard than Quartz, but Ilrikes fire with fteel : fpecific gravity 
from 2,272. to 2,594. contains filica 62,8}. alumina 17,02'. 
potafs 16,00. lime 3, CO. oxyde of iron 1,00. Vau^uelini 
''>arialile. Of a vivadous luftre, refledling various colours in certain 
politions of light, of a foliated texture, breaking in- 
to rhomboidal fragments w'ith 4 fpecular facesw 
Labradorttein. Lejk. Naturf. 12. />. 145. 
Labradore Hone. Kir^an mineral, i.f. 324, 
Labradore Felipar. nomfen chem. 3. /. 555. 
Labrador ftone. Sehmei^er mineral, i. 
Found on the Lalraelore coajl, the illand St. Paul’s^ in Various 
parts of America and Europe, in round maffes and detached, 
and often containing Scorl, Mica, and Pyrites : colour 
dark or light grey, diaphanous or femipeliucid, receiving a 
high polifh, and reflefting various colours of blue, purple, 
red, green, &c. in certain pofitions, in fpots or Itripes : 
fpecific gravity from 2,6700. to 2,6925. . 
^“nare. Pellucid, white, of a high luftre, and ftraight lantellar 
' texture, breaking into rhonuboidal fragments. 
Moon-Ilone. Kirn.van. mineral. 1. p. 322. 
Moonftone. Schmeijfer min. \. p. 1 36. 
Pure Felfpar. Thomfon chem, 3. p. 555. 
Found in Ceylon and Snuitzerland, Bohemia and Saxony, in folid 
mafles and alfo cryftallized ; the cryllals rhomboidal, of irre- 
gular angular broad 6.fided columns terminating in pyramidt 
and in reftangular 4-fid. d plates: colour white, with forae- 
times a fliade of yellow, green or red, the furface often re- 
flefting iridefeent colours: the fragments often appear ftri- 
ated : fpecific gravity 2,559. contains filica 64. alumina 20. 
potafs 1 4 : lime 2. i'avqttclin. 
Fibrous, with the fibres parallel and in diftintft layers. 
Lindackeo ap, J. Mayer Samml, PhyJ'.Auff 2 p. 278. 
Found fcattcrcdly in B.hemia, veitli frequently the vefliges of 
quartz or mica ; colour uiually brown : ihining iritcriiaily 
like mother of pearl, breaking into indeterminate fragments, 
and it harder than rock-cryilal. 
