The body of Medici porcelain ware is a type of soft-paste porcelain, composed of white clay containing powdered feldspar, calcium phosphate and wollastonite (CaSiO3), with quartz. The glaze contains calcium phosphate, indicating that the middle-eastern technique of using calcined bone to make an opaque white glaze was adopted. The result is translucent but slightly glassy in feel. Following the precedents of classic Chinese blue and white porcelain, decorations were painted in underglaze blue, which resulted in a range of hues when fired—from a bright cobalt blue (such as a flask in the National Gallery of Art) to grey (such as the bottle detail at right). Some pieces have outlines traced in manganese.