FreshWater Pearl

     Pearls are lustrous gems produced by certain Moilusks. They consist of thin concentric layers of carbonate of lime interstratified with animal membrane, and are the result of an unusual secretion, primarily caused by the introduction of a parasite or some other object within the mantle.

The exact composition of a pearl is as follows :
Carbonate of lime 91.72%
Organic matter 5-94%
Water 2.34%

These gems are divided into two classes, known as Oriental and Fresh- Water Pearls. The Oriental, or Ocean Pearl, is produced by the Avicula Maryaritifera, or Pearl Oyster. Of this bivalve there are many varieties all differing in size, color, weight and quality of the shell. The most important Oriental Pearl Fisheries are the iollowing: Ceylon, Australia, Gambier, South Sea Islands, Arabian Sea, Bands, Costa Rica, Aroe, Haiti, Manilla, Venezuela, Panama and Lower California.

The FreshWater Pearl is produced by a mussel known as Unio Margaritifera. This name is applied to the mussels of our country. The name Naiades is a more general term and includes all freshwater mussels, which are distributed over the entire globe and are found throughout the streams and lakes of all continents, as well as all the larger islands and some smaller islands.

The Unio Margaritifera is very common in North America and especially in the United States. These have a large variety of species also, and there are known to be living in North America nearly 600 different species of them. Most of these are found in the Mississippi drainage area and other streams emptying into the Gulf of Mexico from the north. Many Mollusks are found in the streams emptying into the Great Lakes and St. Lawrence River. Many are also found in rivers that flow into the Atlantic Ocean. The rivers emptying into the Pacific Ocean do not contain many Mollusks and are not known as pearl streams.

Most of the FreshWater Pearls come from the United States. We shall give our attention almost entirely to subjects relating to FreshWater Pearls. Most of the Unionidae are Margaritiferous, or pearl bearing, although many of these varieties are uncommon and so we get most of our pearls from the varieties that are most abundant. Although these are very plentiful, the pearls are very scarce and one has no assurance of finding a pearl in a given number of shells. In some localities there are more pearls than other places; yet they are scarce, everywhere. This is not a bad feature after all as the scarcity of the pearls increases the value of the few that are found.