Also iwamono 岩物. A paint *enogu 絵具 made from pulverized mineral pigments *ganryō 顔料 such as rock, earth, and metals. Used in Japanese painting *nihonga 日本画 and other Oriental painting tōyōga 東洋画. Mineral pigments are insoluble in water, so they are applied with a binder *baizai 媒剤 of animal skin glue *nikawa 膠. Iwa enogu made from naturally occurring materials include: ultramarine *gunjō 群青 made from azurite or lapis lazuri; green *rokushō 緑青 made from malachite; reds *shu 朱 from cinnabar; *taisha 代赭 from iron oxide; orange *tan 丹 from oxidized lead; yellow ochre *ōdo 黄土 made from native earth colored with hydrated iron oxide; and white *gofun 胡粉 from calcium carbonate obtained from shells. Naturally occurring minerals give the paints the glint and transparency of precious stones. The colors are opaque, durable, and relatively resistant to fading. A single type of stone has a richness of color derived from differences in the sizes of the particles and the inclusion of some extraneous material. Although the number of color sources is limited, various color tones are obtained by grinding down the pigment; the finer the grains, the lighter the shade produced. Exposed to heat, the colors deepen, and even longer heating turns them to a shade of black with a hint of the original color. Iwa enogu must be totally dry before they can be painted over with another color, and it is difficult to mix colors because of differences in the weight and size of the particles. In modern times many Japanese painters use synthetically produced mineral-based paints called shin iwa enogu 新岩絵具 or jinzō iwa enogu 人造岩絵具. Paints made from earth materials are also known as doro enogu 泥絵具.