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 Medieval Ages refer to the period from 5th to 15th century. Dark Ages refers to the period characterized by the deterioration in the economic and cultural situations in Europe. Historians roughly fix the period as the period of Early Middle Ages. It is between 400 AD and 1000 AD. This is the period between the fall of the Roman Empire and the High Middle ages.