Navegando por Autor "HOHN, Helmut"

Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
Jarina: o marfim das biojóias da Amazônia
(2006-12) COSTA, Marcondes Lima da; RODRIGUES, Suyanne Flavia Santos; HOHN, Helmut
The jarina palm tree (Phytelephas macrocarpa) is endemic of the Amazon region growing in older flood plains constituted by quartz, 2:1 clay-minerals and feldspars. The soils are fertile and slightly acid to neutral. The jarina seeds can be included among the rare organic gems. Because of its color and luster the seeds are compared to animal ivory in spite of its lower hardness and lower density. They are largely employed in the manufacture of bio-jewels and artifacts. The products are commercially well accepted because the seeds support coloration change and other improvements. However, the jewels do not last very long because the seeds tend to be destroyed by the action of microorganisms within 5 to 10 years. By means of an adequate policy the productive chain of jarina seeds may turn to be of great importance for the development of the Amazon region by creating new job opportunities and by aggregating value to the products. However, special care has to be taken to avoid inadequate exploration of the seeds in order to assure the preservation of the species.
Acesso aberto (Open Access)
Ocorrência de ostras perlíferas no Marajó, rio Pará
(2002-03) HOHN, Helmut; COSTA, Marcondes Lima da
The occurrence of perliferous freshwater oysters in the southern region of Marajó Island, at the mouth of Amazon River, is reported. The oyster's shell presents a thick layer of conchioline. A set of 12 freshwater pearls present white to dark gray colors with nacarous luster, some with golden metallic hue; sizes from 3 to 11 mm and spheric to cylindrical (with belts) to barroc forms. At long wave UV light, two samples present strong and one presents medium blue color. Paler blue colors are shown at short wave UV light. The inner side of the shell presents pale blue colors at both, long and short wave UV light. This occurrence represents, probably, the first important region in Brazil with natural pearls, opening a perspective for freshwater pearl cultivation.