The average typing speed is 38-40 words per minute (wpm) for adults  in a professional working environment (despite many incorrect  reports on the web that it is 50-60 wpm).
Chronic Health Effects The following chronic (long-term) health effects can occur at some time after exposure to Mica and can last for months or years: Cancer Hazard * Some Silicas have been shown to cause cancer in animals. The risk of cancer in humans from Mica is unclear at this time.
The commercially important micas are muscovite and phlogopite, which are used in a variety of applications. Micaâs value is based on several of its unique physical properties. The crystalline structure of mica forms layers that can be split or delaminated into thin sheets usually causing foliation in rocks.ll are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition. The nearly perfect cleavage, which is the most prominent characteristic of mica, is explained by the hexagonal sheet-like arrangement of its atoms.