Identifying minerals by eye takes a lot of time and practice
minerals come in their own specific crystal form, hardness, streak, lustre and colour and rarely vary from, what type of rock they are coming from, eg. metamorphic, sedimentary or igneous and getting to learn those differences is what helps you identify them.
You start with the common ones, quartz, and some of it's family ... eg. agate and chalcedony both varieties which are often found in an amorphous state
eg ...
if you have a silver/grey metallic looking and cubic crystal form mineral it is a high probability that it is Galena (PbS = Lead Sulphide)
Calcite is usually easily recognisable mainly due to its colour ( usually lack of) and it's crystal form
as time goes by, you add more to the list of ones that you rarely misidentify
I can readily identify 40 to 50 minerals at a glance and a bunch more with a closer study
Other minerals are radio-active, others are fluorescent under UV light giving off specific colours under UV
Many years ago, when I was doing geology at university I was able to make use of the trickier methods of mineral ID
Thin section, XRD and XRF
Thin section ... Petrology
this one is an awesome skill to become familiar with ... just preparing the slides is an art form in itself
commonly used for igneous and metamorphic rocks where there may be no easily visually distinguishable minerals ... their presence becomes very obvious in a thin section slide under a microscope> Again, it takes time and practice ( experience) to learn to identify the minerals in the thin section you are looking at
http://www.bing.com/search?q=manual+thin+section+slide+preparation&FORM=HDRSC1
http://www.bing.com/images/search?q...thin+section+slides+of+rock+samples&FORM=IGRE
http://www.bing.com/search?q=petrol...8-9&sk=&cvid=89339CF4E8CA43CEBB285658C64D0A9B
XRD ... X-Ray Diffraction
http://www.bing.com/search?q=XRD+mi...earchBox&FORM=IENTTR&conversationid=&pc=EUPP_
XRF ... X-Ray Flourescence
http://www.bing.com/search?q=XRF+mi...-26&sk=&cvid=7600D0D1FE7D44E98F9F0A8D4F007D24hope the last two posts help you
feel free to ask other questionsDave