求琥珀的英文介绍

给你一个《大英百科全书》上的介绍：

AMBER: fossil tree resin that has achieved a stable state through loss of volatile constituents and chemical change after burial in the ground. Amber has been found throughout the world, but the largest and most significant deposits occur along the shores of the Baltic Sea in sands 40,000,000 to 60,000,000 years old.

Amber occurs as irregular nodules, rods, or droplike shapes in all shades of yellow with nuances of orange, brown, and, rarely, red. Milky-white opaque varieties are called bone amber. The turbidity of some amber is caused by inclusions of many minute air bubbles. Many hundreds of species of fossil insects and plants are found as inclusions. Deeply coloured translucent to transparent amber is prized as gem material.

Modern investigative techniques are directed toward isolating and identifying as many as possible of the individual resin components and, ultimately, to establishing a genetic relationship between fossil res