Other
Web ref.org: Manganese
A nice set of paragraphs summarizing basic information on manganese, its properties and applications. Well done links on all technical terms and vocabulary.
US Environmental Protection Agency
Epa: Air Toxics Website Manganese Compounds
Very thorough information on manganese. Lists its uses, where it is found, physical properties, and potential health effects.
Corrosion Source
Corrosion Source: Manganese
This resource presents a good summary of the history, properties, sources, uses and handling concerns of manganese. Also contains some basic data.