hOW DO YOU KNOW THE DIFFERENCE ?
Not easy, but if you look close you'll notice that the brass is dull in color, manganese is brighter. A file would confirm it, but you don't want to destroy that gesr ;D.. they are both brass, the manganese is added to make it much stronger and it is used for gears. I think brass is made out of copper and tin :-\ . I would go with bright vs dull...brighter is usually manganese.
not sure. i'm also not sure that brass is actually used in gears because it is so soft. i found this with a google search.
http://en.wikipedia.org/wiki/Brass
Quote
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.[1]
In comparison, bronze is principally an alloy of copper and tin.[2] Bronze does not necessarily contain tin, and a variety of alloys of copper, including alloys with arsenic, phosphorus, aluminium, manganese, and silicon, are commonly termed "bronze". The term is applied to a variety of brasses and the distinction is largely historical.[3]
Brass is a substitutional alloy. It is used for decoration for its bright gold-like appearance; for applications where low friction is required such as locks, gears, bearings, doorknobs, ammunition, and valves; for plumbing and electrical applications; and extensively in musical instruments such as horns and bells for its acoustic properties. It is also used in zippers. Because it is softer than most other metals in general use, brass is often used in situations where it is important that sparks not be struck, as in fittings and tools around explosive gases.[4]
I agree - in my experience, it's generally bronze (the tin is effectively a hardener).