Reference work entry
This is a carbonate clump in loess. Carbonate (CaCO 3, MgCO 3) solution moves through the loess pores or along vertical joints and aggregates into nodules of irregular rods, spheres or clumps. A calcic nodule layer forms when these nodules accumulate in a layer. Calcic nodules are common in loess. Because the nodules are shaped like a piece of ginger, they are also called ‘ginger stone’. Calcic nodules are important ornamental stones because of their unusual shapes. A piece of calcic nodule that resembles the shape of a lady was discovered in the Xiashu Loess in Nanjing. This nodule was later called ‘Lady Mochou’ and became well known when exhibited. It is considered a priceless treasure (Fig. 4).
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