144 FRAUENEIS. 



green isli- brown colour, and remains trans- 

 parent. 



Soluble, without effervescence, in heated 

 muriatic acid. 



Localities. Extensive veins of Franklinite 

 Ore are found in Sussex county, New Jersey, 

 about seventy miles from New York. It is 

 also said to occur, in amorphous masses, ac- 

 companying ores of zinc, at the mines of 

 Altenberg, near Aix-la-Chapelle, and in the 

 mines of Breithek and Victoria, in Nassau. 



Franklinite strongl}^ resembles Oxidulated 

 Iron, but may be distinguished from it by 

 yielding a dark reddish-brown streak, that 

 of the latter mineral being black. Chemi- 

 cally Franklinite differs from it by contain- 

 ing the oxides of zinc and manganese. The 

 per cent age of zinc is very variable, ranging 

 from 21 per cent., in the ciystals, to as much 

 as 26 per cent, in the massive ore. The per 

 centage of iron varies from 55 to 65, that of 

 manganese from 12 to 16. 



The oxides of zinc and manganese appear 

 to exercise a very favourable influence upon 

 the iron manufactured from this ore. Its 

 tenacity is found to be very great, and it is 

 stated to resist the attacks of oxygen (rusting) 

 in a remarkable degree. It is also readily 

 converted into steel, suited for the finest cut- 

 lery and razors, a result which is probably 

 facilitated by the presence of manganese. 

 In fact, the metal made from this ore is a 

 coarse steel, and differs very greatly from 

 ordinary pig-iron. It is also said that 

 Franklinite smelted with Anthracite or Coal 

 affords as good iron as can be made with 

 charcoal, which is supposed to be caused by 

 the zinc, when volatilized, carrying off Avith 

 it any sulphur or phosphorus that the coal 

 may contain. Franklinite pig-iron is repre- 

 sented as capable of bearing a tensile strain 

 of 40,000 lbs. per square inch, or to be nearly 

 double the average strength of the iron used 

 b}^ the British Government for casting heavy 

 guns. 



Name. After the celebrated Benjamin 

 Franklin. 



Brit. Mus., Case 26, 



Fkaueneis, Werner. See Selenite. 



Freibergitb, Argentiferous Tetrahe- 

 drite ; the Polytelite of Glocker, 



Analysis, from Freiberg, by Rose ; 

 Sulphur . . . .21-17 

 Antimony . . . c 24'G3 



Copper 14-81 



Iron 5-98 



Zinc 0-99 



Silver ..... 31-29 



98-87 



FRUGARDIT. 



Freieslebenite, Haidinger. Oblique, Oc- 

 curs in small deeply striated crystals, which 

 are irregularly associated, but more often 

 separate. Colour and streak pale steel-grey, 

 inclining to silver- Avhite ; also blackish lead- 

 grey. Lustre metallic, externally shining 

 and splendent. Yields readily to the knife, 

 and is easily susceptible of mechanical divi- 

 sion parallel to the planes of a right rhombic 

 prism. Extremelv brittle. Fracture con- 

 choidal, uneven. H. 2 to 2-5. S.G. 6 to 6-4. 

 Camp. Sulphantimonide of silver and 

 lead, o'r(Pb, Ag) S + Sb^SS. 

 Analysis by Wohler : 



S-alphur .... 18-77 

 Antimony .... 27'72 

 Lead ..... 30-00 

 Silver . . . . . 22-18 



Iron 0-11 



Copper i -62 



100-00 



BE emits copious white vapours, and a 

 slight sulphurous odour ; deposits oxides of 

 antimony and lead round the assay, and 

 finally a small white globule of silver re- 

 mains. 



Localities. The Himmelsfurst Mine, at 

 Freiberg, in Saxony, Kapnik, in Transyl- 

 vania. Ratieborzitz. Abundant at Hiende- 

 laencina in Spain. 



M. P. G. Principal Floor, Wall-case 14 

 (British). 



Name. After Freiesleben. 



French Chalk. A white or greyish kind 

 of Steatite, used for taking grease out of silk, 

 and also for slate-pencils, which are made 

 in a similar manner to ordinary lead-pen- 

 cils. It is also used, in a state of powder, to 

 make new gloves and boots slip on easily 



M. P. G. Horse-shoe Case, Nos. 1055, 

 1056. 



Friable Lithomarge. Usually massive, 

 also as a crust, and composed of fine shaly 

 particles. Colour snow-white or yellowish- 

 white. Lustre glimmering. Adheres to the 

 tongue and feels greasy. 



Locality. Saxony, in tin-veins. 



Frugardit or Frugardite. A variety 

 of Idocrase, fron Frugard, in Finland. 



Analysis, by Nordenskiold : 



Silica 38-53 



Alumina 



Protoxide of iron 



Lime . 



Magnesia 



Protoxide of manganese 



. 17-40 

 . 3-90 

 . 27-70 

 . 10-60 

 . 0-33 



98-46 



