What is the structure of powdered sulfur?
Powdered sulphur is produced by grinding raw sulphur as it is mined. According to Wikipedia, mining is done as follows:


  On Earth, elemental sulfur can be found near hot springs and volcanic regions in many parts of the world, especially along the Pacific Ring of Fire; such volcanic deposits are currently mined in Indonesia, Chile, and Japan. Such deposits are polycrystalline, with the largest documented single crystal measuring 22×16×11 cm.[21] Historically, Sicily was a large source of sulfur in the Industrial Revolution.[22]


Raw sulphur is polycrystalline (meaning many crystals grown together). So basically, powdered sulphur is the same as crystalline sulphur just as very small crystals. Consequently, what you found in that paper for crystalline sulphur also applies to powdered sulphur.