562 ANTSrUAL REPORT SMITHSONIAN INSTITUTION, 1961 



hematite, limonite, and pyrolusite, mixed in various proportions with 

 silicate minerals, have enjoyed an important place on the artist's palette 

 going back to the prehistoric cave paintings of France and Spain. 

 They are plentiful and cheap. The Egyptians, employing earth pig- 

 ments, decorated tombs with incredibly fine and realistic paintings, 

 as did the pre-Columbian Indians who painted designs on the walls of 

 their kivas in the American Southwest. If one observes carefully the 

 flesh tone of figures done in tempera technique by the Italian masters 

 of the Middle Ages he will see that they are underpainted with a 

 greenish pigment. This is a native earth appropriately called terra 

 verde (green earth). It is made up principally of glauconite (also 

 called celadonite) , a complex mineral composed principally of potas- 

 sium, iron, and aluminum silicates. These earth greens serve well 

 in the tempera medium of the Italian masters, but they are too low 

 in refractive index to be used in oil. 



In the early times, bright blue pigments were rare and highly 

 valued, sending painters' suppliers to the remotest parts of the then 

 known world to find sources of lapis lazuli (lazurite) and azurite, the 

 only two blue minerals which had the necessary properties to make 

 them good paint pigments. Only one important source of lapis 

 lazuli was known in antiquity, and that was in a distant and remote 

 valley in Asia near the source of the Oxus River in the mountains 

 of the Hindu Kush [26]. Here in the northeast province of Afghan- 

 istan, called Badakshan, are the lapis lazuli mines that were visited 

 by Marco Polo on one of his trips to China, and there is good reason 

 to believe that these mines were worked long before the Christian Era. 

 The Sumerians in the third millennium B.C. used lapis lazuli to 

 ornament gold, and it has already been mentioned that their successors, 

 the Babylonians and Assyrians, used it for cylinder seals. It was 

 known very early that lapis lazuli, when ground to a powder, yielded 

 a deep bright blue pigment suitable for making paint. In the West, 

 lapis lazuli apparently first began to be used as a pigment in Byzan- 

 tium in the early Middle Ages. At this time, the blue stone was 

 carried across Central Asia over the "silk routes" to the Levantine 

 port of Acre and thence by sea to Venice. A method was invented 

 which permitted the separation of blue particles in impure ground 

 lazurite from colorless gangue materials in a way which is similar 

 to modern flotation processes for the beneficiation of metallic ores. 

 The medieval Italians called the blue pigment "ultramarine," because 

 its source was from "beyond the sea." The Renaissance painters em- 

 ployed it to paint the Virgin's robe and to represent distant mountain 

 landscapes and the vault of heaven. Ultramarine, along with gold, 

 was specifically named in contracts given by patrons to painters, and 

 early account books speak of its costliness and special worth. About 



