From last quarter but an interesting story.
I always thought amber was translucent because that was all the amber I had seen but it turns out that much amber is opaque because it contains impurities. Well that sucks, how can you see what's in it? No problem if you have access to the European Synchrotron Radiation Facility - that sucker can 'see' through anything using a high-contrast, high-resolution form of X-ray radiography.
There's a report on the National Geographic website but check out the report on the BBC website, it's much better and the video is really cool.