Min. [see CALC-.] A porous deposit of carbonate of lime, formed by the waters of calcareous springs; calcareous tufa.
1822. Mrs. Lowry, Convers. Min., II. 265. Acidiferous Earthy Minerals … Calc-tuff.
1857. Page, Adv. Text-bk. Geol., xx. (1876), 420. Calc-tuff … is an open, porous, and somewhat earthy deposition of carbonate of lime from calcareous springs.
1863. Watts, Dict. Chem., I. 722. Calctuff, an alluvial form of carbonate of calcium.
