MINERALOGY. 



ccaiverted into a metallic globule, imbedded in a vitreous 

 fcoria. 



" In all cafes where a metallic globule is obtained, it (hould 

 be feparated from the adhering fcoria, and examined as to 

 it-s malleability and other external charafters ; being then 

 placed a fecond time on the charcoal, but without flux, it is 

 to be brought to a ftate of gentle ebuUition, during which 

 the furface being oxygenated, will exhale a heavy vapour 

 that condenfes on the blow-pipe, or falls down on the char- 

 coal in form of a powder, or of fpicular cryftals, from the 

 colour and other charafters of which the nature of the 

 metal may probably be afcertained. If any fufpicion is 

 entertained of a portion of filver or of gold being mixed 

 with the oxydable metal, the button muft be placed on an 

 earthen fupport, and there brought to a full melting heat ; 

 by degrees the oxydable metal will become fcorified, and 

 will entirely link into the fupport, leaving on the furface a 

 bright bead oijine metal, if fucli was contained in the alloy ; 

 but the proportion of this laft being generally very fmaU, 

 and the entire mafs of the alloy often not exceeding a large 

 {hot, it is not unfrequently neceflary to have recourfe to the 

 magnifying glafs, to be fully convinced of the prefence or 

 abfence of fine metal." Aikin's Manual of Mineralogy. 



The above directions will be found of the greateft ufe, 

 and are fufficiently ample to make any additional remarks 

 unnecefTary. Some German mineralogifts have, indeed, 

 arranged under nearly one hundred heads, the different 

 changes produced on minerals by the aftion of the blow- 

 pipe, and have given elaborate explanations of words known 

 with fufficient accuracy by almoil every child of feven 

 years of age. This we regard not as fmoothing the paths 

 of fcience, but as blocking them up with rubbifh to impede 

 the progrefs of the ftudent. 



In the mineralogy of Haliy, he has introduced very 

 judicioufly what he denominates the dijlin8i-ve charaScrs of 

 minerals, noting the particular characters which ferve to 

 dillinguiih one mineral fpecies from another, to which it 

 has the greateft general refemblance. 



New fpecies of minerals have been difcovered almoft 

 every year fince the commencement of the prefent century, 

 the greateft number of thefe difcoveries have been made in 

 the mines of Sweden. Few, however, of the newly dif- 

 covered minerals poffefs properties that entitle them to 

 much notice, and it is highly probable, that as the fcience 

 of mineralogy advances to perfeftion, many of thefe fup- 

 pofed new fpecies will be difcovered to be only varieties of 

 fpecies that have been long known. 



AcTiNOLlTE, or ABynolite. Fr. alfinote. See Strahl- 



STEIN. 



AcTlNOTE, Amph'ibole. See Strahlstein. 



Adamantine Spar, or Common Corundum ; Corlndon 

 harmophane, Haiiy. See Adamantine Spar. 



Adhesive Slate, a fpecies of polifliing flate, or polier 

 fchijle. See Polishing Slate, Addenda. 



Adularia. (See Felspar, Addenda.) This variety 

 of felfpar was formerly confounded with glafly felfpar. ( See 

 Glassy Felfpar, Addenda.) Adularia occurs in veins of 

 granite in Bamfshire, in the Ifle of Arran, and other parts 

 of Scotland. Rolled pieces of adularia having a moft 

 beautiful pearly light are found in the ifland of Ceylon. 



Agalmatolite, or Figure-Stone ; Beldjlein, Werner ; 

 Talc graph'ique, Haiiy. A mineral which may be regarded 

 as an indurated fteatite, or rather, according to Jamefon, as 

 intermediate between fteatite and nephrite or jade. It 

 occurs maffive; the frafture is fplintery, or imperfedlly 

 flaty ; the colours are greenifti-giey, apple -green, or yel- 

 lowilh-brown, and fometimes flelh-red and rofe-red. It is 



tranflucent, unftuous to the touch, and yields witli eaie lo 

 the knife, owing to which property it is carved with 

 facility into different figures by the Chinefe, and into 

 pagodas, cups, and fnuff-boxes. The fpecific gravity is 

 from 2.6 to 2.8. According to Klaproth, the conftituent 

 parts of agalmatolite are. 



Silex 



Alumine 



Lime 



Potafh 



Iron 



Water 



According to Aikin, this mineral occurs at Glyder Bach, 

 Caernarvonftiire. 



Agaric Mineral, or Rock Mill ; Chaiix carbonatee fpon- 

 gienx, Haiiy. See Agaric Mineral. 



Agate. (See Agate.) The agate is not a fimple 

 mineral, but is compofed of various filiceous fubftances 

 arranged in concentric lamella;, exhibiting, when cut and 

 poliftied, zones and angular lines, hke fortifications. There 

 is alfo a kind of agate-breccia, in which angular fragments 

 are cemented by quartz or chalcedony. Agates appear to 

 be formed by filiceous infiltration in the cavities of bafaltic 

 rocks, the formation commencing from the furface, and the 

 cavity gradually filling by fucceflive depofitions on the fides, 

 until the whole forms one folid nodule. According to the 

 direftion of the lines or the ftrufture of agates, they are 

 denominated ribbon or Jlriped agate, fortijication agate, land- 

 fcape agate, brecciated agate, tabular agate, jeifper agate, 

 /potted agate, blended agate, Jlar agate, marked with radi- 

 ated fpots ; petrifaRion agate, foflil-fhells and zoophytes 

 are fometimes penetrated or fiUed with agate. In the variety 

 called mofs agate, nodules of chalcedony inclofe minute 

 arborizations rcfembling mofs, fome of which are fuppofed 

 by mineralogifts to be branches of mofs fuddenly inclofed and 

 preferved in filiceous matter. 



Alabaster, Calcareous, or Calcjinter Alabqfler, Gypfeous 

 Alabajler. See Alabaster and Gypsum. 



Alalite, Diopjide, and MuJJite, a mineral aUied to augit ; 

 firft found in the Alp of La Mufla, near the town of Ala, 

 from whence the names alalite and muffite are derived. 

 See DiOPSlDE, Addenda. 



Allanite, Cerium allanite, Fr. an ore of the newly- 

 difcovered metal cerium, firft analyfed by Mr. Allan, and 

 hence called allanite. Its colour is a brownifh-black ; it 

 occurs difll'ininated and cryftallized in rhomboidal prifms, 

 the angles of which meafure 117° and 63°. The internal 

 luftre is (hining, and refino-metallic. It is opaque, and 

 yields a greenifh-grey ftreak. It fcratches glafs, is brittle 

 and eafily frangible. Before the blow-pipe it froths, and 

 melts into a brown flag. It gelatinizes in nitric acid. The 

 fpecific gravity is from 3.5 to 4. The conftituent parts 

 are, 



Oxyd of cerium - - 33.9 



Oxyd of iron - - 25.4 



Silex - . . . 35.4 



Lime .... 9.2 



Alumine - - - 4.1 



Moifture . • . . 4 



It occurs in granite in Weft Greenland. 



Allochroite, 



