Lighting can be tricky due to the differences in colour temperature. The best option is to use daylight globes or equivalent. Daylight globes have a colour temperature of around 6,500 Kelvin. See Wikipedia article on colour temperature.
Heat can be a problem, particularly if you have heat-sensitive minerals, and the lighting is close (eg: under your microscope). Standard globes or halogen lights can get quite hot. Light emitting diodes or LEDs, are becoming readily available and offer the dual benefit of low temperature and low power usage.
I previously used daylight compact fluorescent globes in my Light Cube and a 144 LED ring light for my microscope. There are a number of ring light models available on eBay for under $100, such as the one pictured.