Basically, there are several types of mining. There are ship wrecks, asteroids and asteroid fields (marked with "AF" after the Planet name in the system overview) in many systems in the Stellar Tactics universe and there are mining nodes on planets.




More info is available on the wiki.
Stellar Tactics Wiki [stellartactics.fandom.com]

Content below from the Wiki - Credits to Cipolla86!

Mining of ship wrecks, asteroids and asteroid fields requires a ship with a good-sized cargo hold and mining turrets to harvest these ores and minerals. The process is the same for all these types: the asteroid or ship wreck has to be approached (be in range of the mining lasers) and the turrets have to be activated. Then a mining laser is selected in the lower left corner of the UI and then the mining target (asteroid or ship wreck) has to be clicked. Asteroids will give ores, minerals and rare earth. Asteroids in Asteroid Fields respawn with time.

Mining Ship wrecks mainly earns rare earth and ship repair components needed to repair boarded ship systems. However, other ores are mined as well. Wrecks can be located when scanning ships or planets in a system. They are indicated by a green ping (see image). The green ping just has to be approached. Ship wrecks contain about 5k-30k ore/rare earth. Once they are depleted, they won't respawn.

When a planet is scanned, there is a chance that there are one or several planetary minig nodes. To mine them, the player needs mining drones, which can be bought at ship equipment vendors on all planetary bases and stations. When a mining drone is available and the node is selected, the mining button can be clicked and the drone will be sent to that node. The mining drones can be set to one of two mining modes in the mining drone menu in the lower left corner of the UI: auto and manual. In both modes the drones mine ore until their cargo is full. The chosen mode determines, what they do when their storage is full. In auto mode: they automatically sell the ore (the Credits are directly sent to your account) and start mining that node again. This will be continue, until the node is depleted. In manual mode, full drones wait for the player to return and pick them up again, which will unload the cargo of the drone to the player's ship's cargo hold. However, full drones can only be retrieved, if there's enough free storage room in the ship's cargo hold. Drones set to manual mode can be picked up before they are full. Afterwards, the drone is in the pool of available drones again, i.e. it has to be sent manually to the node (or another node) again to continue mining.

Depleted mining nodes do not recharge or respawn!

You can purchase and equip a refinery on your ship. Refineries let you convert raw ore to refined ore – a more valuable commodity. Refined ore is used for crafting items and traded across the Universe on the Trade-Net. You can purchase and equip a refinery at any ship equipment vendor. Like all ship equipment, refineries are ship specific so you cannot swap them between ships. Refineries equip to your ship's “hardware mount point”. The efficiency of the refinery determines the amount of waste produced during the refining process. A refinery with 50% efficiency produces up to 5 units of waste (of raw ore) per refined unit, a refinery with 100% efficiency produces 0 waste of raw ore per refined unit. See some examples in the table below.

You can refine anywhere - in mission areas, in space, it doesn't matter - as long as you have ore in your cargo hold. So, you could have a ship with a large cargo hold full of ore and go complete a ground mission while all that ore is being refined.

Mining perks enhance refining so the process is more efficient. This means less waste, less required units of raw ore per refined unit and less time per refined unit.

Credits to Cipolla86