A soft, earthy, dark-coloured rock or clay derived from the alteration of basalt. (noun)
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Use "wacke" in a sentence
"The house has a dark look, being built of the native whinstone, or grau-wacke, as the Germans call it, relieved by the quoins and projections of the windows and turrets in freestone."
"The basis of these lower lavas is rather wacke than basalt; when it is spongy, it resembles the amygdaloids* of Frankfort-on-the-Main."
"This regular disposition of lithoid basaltic lava and feldsparry vitreous lava is analogous to the phenomena of all trappean mountains; it reminds us of those phonolites lying in very ancient basalts, those close mixtures of augite and feldspar which cover the hills of wacke or porous amygdaloids: but why are the porphyritic or feldsparry lavas of the Peak found only on the summit of the volcano?"