326 



in small crystals of an olive brown, remarkable for their lustre, in por- 

 phyry, at Sandy Braes. 



Ilydrophane, of a brownish- white colour, occurs in amygdaloid, near 

 the Giant's Causeway; and at Crossreagh, parish of Ballywillin. 



Jasper, in the porphyry, on the shore near Cushendall. 



LaumoniU is found at Larne ; at Portrush rarely \ at Ballintoy, 

 with Stilbite. 



Levyne occurs at Little Deerpark, Glenarm, in small distinct 

 translucent crystals ; in trap, with Mesotype ; at Island Magee, of a 

 yellowish-white, or pale flesh-colour. 



Lignite (see p. 320 et seq.). Also in Rathlin Island. 



Lithomarge, of greenish- white colour, highly indurated, is found in 

 masses in the trap rocks at Dunluce ; also at Port Brad den ; at Ballin- 

 toy ; and at Sallagh Braes, near Larne. 



Magnetite, or Magnetic iron ore, is found in amygdaloid at Island 

 Magee, and the Isle of Muck, near it. 



Mesole — Faroelite (see also Apophyllite, Augite). 



Mesolite is found in fine acieular crystals at the Giant's Causeway 

 (see also under Faroelite). 



Mesotype (see under Analcime, Gmelinite, Levyne.) 



Micaceous Iron Ore is got at Island Magee in crystals and tables, dis- 

 seminated through, and forming irregular strings or veins in claystone. 



Natrolite occurs at Carncastle ; at the Little Deerpark, with Cal- 

 cite in trap, and in delicate silky crystals in amygdaloidal claystone ; 

 occasionally at the Causeway ; at Ardihannon Cove ; at Portrush ; at 

 Little Deerpark, snow-white, sometimes brownish - white ; at Island 

 Magee, near Larne, in fine crystals, and radiating masses ; at the Cave 

 Hill, Belfast, fibrous and compact, of a pale-red colour in trap. 



Octahedral Iron Ore is got at Isle of Muck, of a fine black colour ; 

 on exposure becoming coated with peroxide of iron, frequently with a 

 tempered steel tarnish. It is got in small, but perfect octahedrons; 

 also in rhombic dodecahedrons. 



Obsidian is found at Sandy Braes. It occurs of velvet-black colour, 

 in the vesicular cavities of fine-grained greenstone at the Causeway, 

 but is rare; also occasionally at Craigahulliar, near Portrush. 



Olivine. — Got in basalt and trap near the Giant's Causeway, of an 

 olive-green colour and brownish, disseminated, and in small crystalline 

 masses; with Augite, atPairhead, in small grains; in trap, at Ballintoy; 

 at Agnew's Hill, partially decomposed, and possessing a semi-metallic 

 lustre ; at White House, near Belfast, of a fine cherry-red colour, and 

 translucent, and in large crystalline concretions in the trap of Island 

 Magee. 



Onyx occurs at the Causeway, in amydgdaloid; on Eathlin Island, 

 striped white and yellowish-brown. 



Opal is found at the Causeway; in Bathlin Island; at Crossreagh, 

 near Coleraine ; at Sandy Braes it is abundant in the pitchstone por- 

 phyry, generally opaque and white ; also, yellow, or reddish-yellow, 

 and highly translucent. 



