no MARINE PRODUCTS OF COMMERCE 



Margaritifera margaritifera mazatlanica, which is closely related to the "black-lip" 

 shell of the Austialian coast. It is considerably larger than the Venezuelan oyster, 

 averaging from 4 to 5 inches in diameter and sometimes attaining 7 or even 8 

 inches. Another species, Margaritifera vinesi, occm-s only in the northern part 

 of the Gulf, near the mouth of the Colorado River. 



The Australian Fishery. Although many fine pearls have been found in the 

 Australian fisheries, they are principally exploited for pearl shells and are, there- 

 fore, described in the section on mother-of-pearl. The value of the pearl yield 

 in the northwest Australian fisheries for 1906 was estimated at £-50,000, that of 

 the Queensland fishery, £33,000, and that of South Australia, £5,000, a total 

 of £88,000, or nearly $430,000. Relatively few seed pearls are secured. Some 

 beautiful examples of large pearls have been found, but they usually possess less 

 lustre than the Persian or Indian product and their form is less regular. 



One of the finest Australian pearls was that taken by one of the luggers of 

 Messrs. James Clark and Company's fleet near Broome, Northwestern Australia, 

 late in 1917. It weighed 100 grains, was 18 mm long, 15 mm in diameter, and 

 had a circumference of 45 mm. The bottom end was flat for a width of 7 mm. 

 This pearl was valued at £20,000. 



Malaysian Fishery. The best known of the Malaysian pearl fisheries are those 

 of the Sulu Archipelago, Philippine Islands. The pearls obtained were available 

 to the rest of the world as long as 400 years ago, and in 1520 Pigopitta, a com- 

 panion of Magellan, reported them to be among the prized possessions of the 

 natives. The pearl-oyster reefs extend from Sibutu Pass to Basilan Strait and 

 roughly cover an area of 15,000 square miles. The large mother-of-pearl oyster, 

 Margaritifera maxima, is by far the most abundant, but the Australian "black- 

 lip," Margaritifera margaritifera, is also found. 



Other Fisheries. Among the pearls which are contained in certain other mol- 

 lusks are pink pearls. They are sometimes found in the Strombus gigas, the giant 

 conch shell of the West Indies. Unfortunately, they are not nacreous and do not 

 preserve their hue very well. Strombus gigas is one of the largest of the univalve 

 shells, some measuring as much as 12 inches in length and weighing 5 or 6 

 pounds. An exceptionally fine example of a conch pearl has been sold in New 

 York for $5,000, the gem having been brought from Nassau in the Bahamas. 

 Pearls are occasionally found in the Turbinella scolymus and in the Indian chank 

 (Turbinella rapa), which produces pink and red varieties. The Pinna squamosa 

 furnishes some brown pearls of poor quality. On the other hand black pearls 

 from the pearl oyster of the Gulf of Mexico command high prices. 



Fresh-water mussel pearls are found in many of the lakes and streams in 

 certain sections of the United States. In the past Iowa and Arkansas were the 

 leading suppliers of fresh-water pearls. These pearls, while often beautiful (fine 

 ones are exceedingly rare), do not command the prices obtained from genuine 

 salt-water pearls of equal size and beauty. It is very difficult to obtain in any 

 quantity fresh-water pearls of approximately the same color, and they are usually 

 more misshapen than the pearls grown in salt water. 



It should be mentioned here that fine pearls are never found in edible oysters. 

 What is sometimes found is nothing more than a gray, worthless calcareous mass 

 or concretion. These so-called "pearls" are in no way related to the pearl found in 

 the shells of Unio or Margaritifera. 



