阅读理解Even though African elephants are protected, many of them are still being killed for their ivory.
At the end of the 1970s, over 1.3 million elephants walked around Africa, but today, their numbers have fallen to around 450,000. This is mainly caused by illegal(非法的) hunting for ivory. Need for ivory in markets, especially in Asia and Africa, continues to push the illegal trade. This has resulted in the deaths of at least 20,000 African elephants each year.
Ivory, also known as "white gold", has long been considered valuable. Its unusual look has led to its use in lots of expensive things, including jewellery, musical instruments and art. And the ivory material itself can stand the test of time. So many people are willing to pay a high price for ivory products.
However, no matter how much real ivory is sold for, it's certainly not worth the harm to elephants. That's why some scientists are working to achieve the same beauty of ivory without killing any animals.
Thaddaa Rath and her team at the University of Vienna have created the ivory called "Digory". The high-tech ivory is made from synthetic resin(合成树脂) and calcium phosphate particles(磷酸钙颗粒). It's first formed into the shape by a 3D printer. And then it is color-matched and colored. Next, it is polished(抛光) to make it look like real natural ivory.
Although Digory looks so real that it is hard to tell it from real ivory, its chemical structure is completely different from that of the real one. Fritz Vollrath, a biologist who is against killing elephants for ivory, felt excited about the invention and spoke highly of it for the fact that Digory could save many elephants from risks. Scientists have made some achievements, but we still need to do more research to make sure that it is widely used. It's still hopeful that scientists can be able to protect African elephants by making high-tech materials to take the place of the real ivory.
