Note that the Orientation Slice is cut precisely to the (100) before the crystal is rotated and cut at either +.25 degrees and toward the flat, or â.25 degrees and away from the flat (as described in Figure 3).
The era was called the Dark Ages also because we don't have a lot of written sources from that time period, especially from the early part of the dark ages (500 to 800 CE).
The term Dark Ages was first used by Italian scholar and historian, Francesco Petrarca who was also known as Petrarch. Being an Italian, he was influenced by the greatness of the ancient Roman Empire. In order to denounce the Latin literature, he coined this phrase.