Calcite crystals from a water-tank

Extract

A crystalline deposit of sufficient interest to warrant description was brought to the authore notice by Mr. Henry Preston, F.G.S., who has recently described its mode of occurrence. The material consists of a white, glistening, crystalline powder, or a sand-like aggregate of minute crystals. It was deposited in a water-tank into which water was led through an old leaden pipe, over a mile in length, from a spring rising from the basal ferruginous beds of the Marlstone (Middle Lias) ill Belton Park, north of Grantham, Lincolnshire. The sand was deposited in the tank as a conical heap, spreading over a base of perhaps four square yards and reaching a height of seven or eight inches at its summit.