There are two types of resources in the game which you can mine, Enmatter and Ores. Enmatters are generally liquids, powders and other aqueous things (such as Oil) while ores tend to be stones and metals (such as Gold and Iron). Different tools are used for each of the two types of mining. If you are just starting out with mining, you will find all the equipment you need in the Trade Terminal under "Tools" and then "Mining".
A set of Enmatter equipment is generally more expensive than Ore equipment, but probes (which are used for Enmatter mining) are half the price of bombs (which are used for Ore mining). Many believe that this makes Enmatter mining cheaper in the long run. Others argue that Ore deposits are larger and have a larger markup price (and therefore more valuable). In reality, both types of mining are probably equal in expense, therefore it probably doesn't matter which type of mining you start out with.