614 MANUAL OF NATURAL HISTORY. 



iron in " Ferro-tantalite," H. 5 — 6 ; sp. gr. 

 = 7*5 ; black, brittle. Symb. Ta. 



3. Family. — Niobiides. Minerals containing com- 



pounds of Niobium. Occur as Niobic acid 

 in "Polycrase," also in "Niobite." Symb. 

 Nb. 



4. Family. — -Pelopiides. Minerals containing com- 



pounds of Pelopium. Occur as Pelopic acid 

 in " Poly erase/' also in " Columbite." Symb. 



pp. 



5. Family. — Ilmeniides. Minerals containing com- 



pounds of Ilmenium. Supposed to exist in 

 " Samarskite." Symb. II. 



6. Family. — Kassiterides. Minerals containing Tin, 



either native, or in combination. Occur J, 

 pure or " Native Tin/' in grains with Siberian 

 gold, sp. gr. 7*2 — ; 2, as Binoxide or " Cas- 

 siterite" or "Tin Ore/' H. = 6*5, sp. gr. = 

 6*8, crystallised, massive, or in grains, 

 brown or black ; 3, as Sulphuret or " Tin- 

 pyrites/' in cubes, H. — 4; sp.gr. — 4*4, steel- 

 gray. Oxide of tin before the blowpipe, 

 with soda, yields metallic tin, and with borax 

 an opal white enamel. Symb. Sn. 



7. Family. — Titaniides. Minerals containing Tita- 



nium, either native or in combination. Oc- 

 cur 1, pure as "Native Titanium/' in copper- 

 red, cubes, in Cornwall, H. = 7, sp. gr. = 5'3 ; 

 2, as Titanic acid or "Rutile," prismatic, 

 H. = Q, sp. gr. = 4*2, reddish brown, also 

 combined with oxide of iron or some other 



