Like the Research Site, the Mining Facility is not a full blown area to explore like some of the others, but it is an area which you must clear out in order to advance. Some abandoned mining equipment can be utilized to gain further access to the area, provided you are able to clear away any obstacles in your path. Digging further into the facility will give you the opportunity to eradicate two more Metroids who hold the key to triggering the next earthquake.
Reaching the mining facility
From the save station just outside of the Industrial Complex, the path to the Mining Facility is mostly devoid of any significant encounter. With the recent earthquake triggered at the Research Site, the lava in room A has receded, allowing you to drop to the bottom of the room. When you get there, you'll find another giant green crystal blocking your path. The only way to get past it is to blow it up with a Super Missile. Then proceed to room B. Both rooms B and C are straight vertical drops with nothing of interest. Fall to the bottom and proceed to room D, where the facility begins.
Investigating the facility
In the middle of room D are two instances of a new species. These creatures have bony masks that shield their bodies from frontal attacks, so they are only vulnerable to attack when they face away from you. Continue to the right to room E. Drop to the bottom and you'll notice an interesting vessel lodged into the rock on the right. Head left to room F, and build up some speed. You will begin to Shinespark and smash through a collection of the bone-faced creatures you saw before.
When you dash into room G, you will hit a wall, but not before breaking some blocks on the floor. Shoot down through the floor to reach the path on the bottom, watch out for the insects waiting below, and return to the right to room H. When you enter room H, you'll see another vessel similar to the one you saw lodged in the rock, sitting out in the open. There is a space in the vessel perfectly sized for the Morph Ball. If you shrink down and roll inside, the vessel will activate. It is actually a mining vehicle, designed to cut straight through rock. It will travel a good distance before reaching another large green crystal, and come to a stop.
As a result of the crystal, it will appear that you are stuck. However, you may notice that there seems to be a narrow passage in the ground. Hop out of the mining vehicle and check the ground. If you bomb around, you will find the opening to the narrow passage, and gain access to a path that takes you ahead of the vehicle and stops directly below the crystal. Aim up and blast the crystal with a Super Missile. Then return to the vehicle and resume your progress. The vehicle will come to another stop, indicating the limit of its ability.
Hop back up, and explore the ceiling around where the vehicle stopped. You should discover a path that takes you above the ceiling, and continues to the right. Once in room I, quickly head over to the room across the way to access a save station and save your progress. Then drop to the bottom of room I. You will have a choice between left and right. You can take either one. For the sake of the walkthrough, head left first.
Room J contains a pool of lava on the floor, as well as odd red bubbles hovering in the air. These bubble won't hurt you, but they do impede your ability to Space Jump effectively above the lava. Be careful as you cross the room, and try to maintain your height in the air. If you hit the bubbles, recover as quickly as possible in order to avoid falling in the lava and taking excess damage. Head to the right to room K
Room K is the nest of an Alpha Metroid. Its room has a pool of lava on the floor as well. It's a good idea not to tempt fate, and keep the fight against the Metroid on the rock in the middle of the room high above the lava. Defeat the Metroid, and then travel all the way to the right, through room J to room I, and on to room L. Room L is very similar to room J, but with a deeper pool of lava. If you happen to fall in, quickly switch to Morph Ball and roll back to the left side to escape.
Once you reach the right side of room L, continue to room M, which is the nest of a more dangerous Gamma Metroid. It also contains quite a few red bubbles which will similarly hinder your progress throughout the room. Once again, position yourself on the platform high above the lava, and attack the Gamma Metroid from there. If you manage to strike it with two Super Missiles, you can end the battle fairly quickly.
Once this Metroid is defeated, the next earthquake will trigger, allowing you to proceed further into the planet. All that is left to do now is to leave the mining facility and return to the top. Remember to Shinespark your way back through room F. When you return to room A, there is actually a shortcut you can take to get you on your way to the next area. The wall in the lower left corner of room A can be destroyed with the Speed Boost. So run along the floor, and stop before you hit the block before this wall (or jump just in time) to smash through the wall, and access the tunnel just outside of the Research Site.
There are no items to obtain throughout this portion of the game.