Take an evening or weekend day and go to a local university chemistry library. Heck, your high school may even have a few of these resources. Look up magnesium hydroxide in the following references:
The Merck Index
Kirk-Othmer Encyclopedia of Chemical Technology
The CRC Handbook of Chemistry and Physics (more quantitative data)
Lange's Handbook of Chemistry (also more quantitative)
You can also check out some more advanced inorganic chemistry texts, like:
Chemistry of the Elements, Greendoow & Earnshaw, Eds.
Advanced Inorganic Chemistry, F.A. Cotton
These will provide information ad nauseum about Mg(OH)2