Note 15 — RAW MATERIALS; COLLECTION, AND PREPARATION

Stevenson, writing of the Zuñis in 1881, said: “The material used to produce the red or brown colors is a yellowish impure clay, colored from oxide of iron; indeed it is mainly clay, but contains some sand and a very small amount of carbonate of lime”; it “is generally found in a hard, stony condition, and is ground in a small stone mortar ... and mixed with water so as to form a thin solution” (1883, p. 330). Mrs. Stevenson added later: “Ferruginous clays which on heating burn to yellow, red, or brown are employed for decorating” (1904, p. 375).