ROESTONE ore which has an exterior crust of black ironstone, and an interior mass of iron-ochre, and in some rarer instances, the centre is hollow, and is encircled with a crust of black ironstone. This nucleus is enveloped in concentric la mellar concretions: the globular concretions are in ge neral imbedded in a base of marl, or are connected to gether without any intermediate substance. It is opaque, or very faintly translucent on the edges. It is semi-hard. It is brittle. It is very easily frangible. Specific gravity, 2.6829, 2.6190, Kopp. Chemical Character. It dissolves with effervescence in acids. Gcognostic Situation. It generally occurs in beds, from lour to twelve inches thick, which alternate with calcareous sandstone, sand- stone-slate, slaty variegated clayey loam, and rarely with red-coloured clay ; and all of these belong to the second fioetz sandstone. Geographic Situation. It occurs in considerable quantity in the province of I'huringia ; and it would appear, from T.scher’s obser- v ations, to be a production of the Jura Mountains *. Uses. The compact and line granular varieties form a good build ng-stone : it is also used us a manure ; but when burnt * F.icher's Brief, in Von Moll's I’Ji., dcr und H uttcnkunUe, e s t. 3. ». 431.
