GELB-BLEIEKZ. 



Anhydrite, found principally at Bochnia and 

 Wieliczkain Poland. 



Gelb BLEiERZ; Gelbes Bleierz, Wer- 

 ner. See WULFENITE. 



Gelbeisenerz. a potash-Copperas re- 

 lated to Jarosite, met with in reniform and 

 in compact eartliy masses in Bohemia, and 

 at Modum in Norway. Colour ochre- yellow. 

 Opaque. Lustre weak. H. 2-5 to 3. S.G. 

 27 to 2-9. 



Analysis, from Brown Coal of Kolosoruk 

 in Bohemia, by Rammelsberg : 



Silica 32-11 



Peroxide of iron . . . 46*74 



Lime 0-G4 



Potash . ■ . . . . 7-88 

 Water 13-56 



100-93 



Gelbeisenstein. See Yellow Ochre. 



Gelberde. See Liimonite. 



Gelberz. See Sylvanite. 



Analysis, by Klaproth : 



Tellurium .... 47*75 



Gold 26-75 



Silver 8-50 



Lead 19-50 



Sulphur .... 0-5 



100-0 



Gelbes Rauschgelb, Werner. See Or- 

 piment. 



Gelf, Kirwan. The name given in Hun- 

 gary to " a particular sort of Argentiferous 

 Copper Pyrites." 



Gelferz. See Chalcopyrite. 



Gem. According to Piiny the ancients 

 included under the term Gem all stones of 

 beautiful colour, Avhich Avere found in small 

 quantity, and of a sufficient degree of hard- 

 ness to be engraved as seals. By Gems the 

 moderns understand those stones which, in a 

 small compass, combine hardness and fire 

 or lustre, with vivid, soft, or agreeable 

 colours, and divide them into two kinds, 

 real gems or jewels and precious stones. 

 The real Gems comprise Diamond. Sapphire, 

 Euby, Spinelle, Emerald, Beryl, Topaz, Zir- 

 con, Garnet, Chrysoberyl, Tourmaline, Ru- 

 bellite, Essonite, Cordierite, lolite, Cyanite 

 (Sappare), Chrysolite, and the varieties of 

 Rock Crystal. 



Precious stones are supposed to possess 

 the same characters as the Gems, only in a 

 minor degree. They are also generally only 

 translucent or semitransparent, and occur 

 in larger amorphous masses. Lapidaries 

 and jewellers name Gems according to their 

 colours, rather than with reference to their 

 chemical composition, or their relative de- 



GEODES. 151 



grees of hardness and density. Thus the 

 Corundum-ruby (Oriental Ruby), Spinelle 

 or Topaz, are all, when red, called Ruby ; if 

 green, Emerald; if blue, Sapphire; and if 

 yellow. Topaz. 



The term Oriental is applied in the same 

 way to the finest stones, whether found in 

 the East or not ; having been used, perhaps, 

 originally to denote those stones which were 

 really brought from the East, and were 

 more highly valued in consequence, than 

 the produce of other countries. In the 

 same way the ancients called the most 

 highly coloured stones masculine, and those 

 of more subdued tints feminine. 



Gemma Pellucidissima, Wallerius. See 

 Emerald. 



Genesee Oil. A kind of Petroleum. See 

 Seneca Oil. 



Geocronite, Dana, Greg ^ Lettsom. 

 Geokronite, Svanherg, Nicol. Rhombic, 

 Usually occurs massive ; also granular or 

 earthy. Colour and streak pale lead-grey. 

 Lustre metallic. Brittle: fracture uneven. 

 H. 2 to 3. S.G. 6-4 to 6-6. 



Comp. Sulphantimonite of lead, or 5 Pb S 

 + (Sb, As) S5 = sulphur 16-5, antimonv 16-7, 

 lead 66-8 = 100. 



Analysis, from Merido, by Sauvage; 

 Sulphur .... 16-90 

 Antimony .... 16-00 



Lead 6489 



Copper . . . .1-60 



99-39 



BB fuses readily, giving off fumes of 

 antimony and sulphur, and colouring the 

 charcoal around yellow. 



Localities,— Irish. Kilbricken, co. Clare. 

 See Kilbrickenite.— Fore/p-K. The silver 

 mines of Sala in Sweden, at which locality 

 a portion of the antimony is replaced by 

 arsemc. In Spain, at Meredo in Gallicia ; 

 and in the valley di Castello, near Pietro 

 Santo in Tuscany. 



Name. The name Geocronite is derived, 

 from r?, earth, and Kpo'v^?, Saturn, the alche- 

 mistic name for lead. 



Brit. Mus., Case 11. 



Geodes. Are net, strictly speaking, 

 distinct minerals, but hollow nodules, fre- 

 l4 



