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).
Petrarch, who conceived the idea of a European Dark Age. From Cycle of Famous Men and Women, Andrea di Bartolo di Bargilla, c. 1450. The Dark Ages is a historical periodization traditionally referring to the Middle Ages. It emphasizes the demographic, cultural and economic deterioration that supposedly occurred in Western Europe following the decline of the Roman Empire, and the relative scarcity of written records from the period.