贝壳的宝石学特征

GEMMOLOGY SPECIFICITY OF SHELL

贝壳和珍珠系同源物质，主要成分为碳酸钙和少量有机质和水分。贝壳为平行层状结构，内层具有美丽的珍珠光泽，银白、洁白色，且质地细腻，半透明至不透明，相对硬度为３～４，密度为２．７５４ｇ／ｃｍ３（白碟贝壳），折光率为１．５３０～１．６８５。在长波紫外线上发亮的兰白色荧光，短波下不明显。贝壳的韧性好，易加工和雕琢成各种精美的装饰品和工艺品，其制品的开发利用已较普及，发展前景日益见好。

Both shell and pearl are from the same origin.Their main sustanies are carbonate,a little part of organic matters and water.Shell has parallel layer texure with beautiful pearly luster.It shows white and smoth , color being subtransparent to nontranspaent. its relative hardness is 3-4,specific gravity is 2.754 g/cm 3 (pinctada maxima shell). Refractive indices is 1.530-1.685.when is put under the long uctraviolet light shows intense blue-white fluorescent,but under the short ultraviolet,the fluorescent isn't obvious.Because shell has good tenacity.it is easy to carve to be some elegant decorations and handicrafts. The shell product has been widpread development. It's prospect and the situation of market will be better and better.