EIEMANNITE. 

 or Striped Jasper. It is fovind at Dressing 

 Green, near Tortworth, in Gloucestershire, 

 at Ballygroggan in the Mull of Cantyre, 

 and is common in Scotland; amongst other 

 localities, at Habbies Howe in the Pentland 

 Hills; at Arthur's Seat, Edinburgh; Stir- 

 lingshire, at Campsie, &c. ; in the Isles of 

 Islay and Rum, &c. The principal foreign 

 localities are Saxony, and the Ural Moun- 

 tains of Siberia. 



Brit. Mus., Case 24. 



Eie:maxxitk. A name for Allophane, 

 after Riemann, by whom it was first ob- 

 served. 



PiiOLiTE, Frohel. A selenide of silver, 

 occurring in small hexagonal tables of a 

 lead-grey colour, at Tasco in Mexico, and 

 named after Del Rio, according to whom 

 its composition is Ag Se^, or silver 67-66, 

 selenium 42-34=100. 



EiPiDOLiTE, Hausmann, Nicol. SeeCHLO- 



RITE. 



RiPiDOLiTE, Rammehberg, Dana, G. Rose. 

 Hexagonal. Occurs in tabular crystals, 

 with perfect basal cleavage. Colour olive- 

 green ; by transmitted light often red across 

 the chief axis. Translucent or nearly trans- 

 parent. Lustre pearly. Strea'k white or 

 greenish. Laminae flexible, but not elastic. 

 H. 1 to 2., S.G. 2-78 to 2-96. 



Comp. R3 Si + Al si + 3H. 



Analysis, from St. Gotthard, by Van-en- 

 trapp : 



Silica 25-37 



Alumina .... 18-50 

 Magnesia .... 17-09 

 Protoxide of iron . . 28-79 



Water . . . • . . 8-96 



98-71 



BB fuses with difficulty at thin edges. 



Soluble in concentrated sulphuric acid. 



Localities. Penrhyn, Caernarvonshire. Ar- 

 gyleshire, in Scotland. Dauphiny. St. Gott- 

 hard, in Switzerland. Ziilerthal, in the 

 Tyrol. Miask, in the Ural. The Harz. The 

 Alps. . Gumush-dagh, in Asia Minor, with 

 Emei-y. 



Name. 'From, pi-"'?, a fan; in allusion to 

 the crystals being often united in comb-like 

 or fan-like groups. For varieties, see Aphro- 



SIDEFJTE. LOPHOITE, OgCOITK. 



Brit. Mus., Case 32. 



Ripidolite is in part Chlorite, and is de- 

 scribed under the latter name by Nicol, Phil- 

 lips, and others. The name was also given 

 bv Yon Kobell to a green Chlorite in grouped 

 folia, found at St. Gotthard, at Rauris in 



ROCK CRYSTAL. 819 



Salzburg, and in the Ziilerthal, with Quartz 

 and crA'stals of Adularia. 



RisiGALT.uM. A name for Realgar, used 

 by the Alchemists. 



RiTTiNGERiTE, Zippe. Probablv a com- 

 pound of sulphide of silver and antimony, 

 and considered by Breithaupt to be iden- 

 tical with Xanthocone. It occurs at Joa- 

 chirasthal in Bohemia, in small rhombic 

 tables with replaced basal edges. Colour 

 iron- black: of cr3'stals brownish- blacki 

 Translucent, and varying from dull honey- 

 yellow to hyacinth-red when viewed by 

 transmitted light, in the direction of the 

 axis. Lustre metallic-adamantine. Streak 

 orange-yellow. Brittle. H. 1-5 to 3. 



Name. After Rittinger, an Austrian 

 officer of mines. 



RocHLAUDiTE. See Serpentine. 



Rock Butter, Jameson. See Petro- 

 leum. 



Rock Cork, Jameson. See Mountain 

 Cork. 



Rock Crystal (from x^va-Totxxo?, ice). 

 The common name for the transparent 

 crystals of Quartz, of which it is the purest 

 form, being composed (according to an 

 analysis by Bucholz) of 99-37 per cent, of 

 silica, Avith a trace of alumina. 



The following are some of the localities 

 where fine specimens of Rock Crystal are 

 found. — English. Cornwall ; at the Tin- 



Fis. 364 



Fig. 36n. 



tagel cliffs and Delabole slate quarries, 

 (.%s. 363 to 365), near Camelford; Huel 

 Mary Ann; Mainporth, near Falmouth, ^^f. 

 365 ;" Carnbrea Mines, yellow ; East Crinnis 

 Mines. Devonshire ; Huel Friendship, near 

 Tavistock ; North Bovey, in large opaque 

 reddish twins, fig. 362. Gloucestershire, 

 figs. 363, 365, at Clifton; known as 

 '■'■Bristol'" or '■'■British diamonds." Ulver- 

 stone Iron Mines. Lancashire, ^/^^f. 364. Der- 

 byshire, at Castleton and Masson Lo'w^. 



