Existence of Essential Minerals on Mars
Mineral deposits are made through Volcanology. Under the crust of Mars, there is a massive collection of magma, consisting of an amalgamation of elements. Over thousands of years, the heaviest of these elements sink to the bottom. These include copper, chromium, nickel and iron, which get concentrated at the bottom of the magma. After even more time, the most of the magma solidifies, and it's in this cooling process that elements bind together to form minerals. The remaining magma consists of elements that do not bind together as minerals, and which are thus called incompatible elements. This collection includes Niobium, which is used in superconductors, and Neodymium, used in powerful magnets.
So you now have two groups: incompatible elements, and minerals. The incompatible minerals usually solidify as-are and are mined with some difficulty. An example on Earth is the niobium mine in South Dakota.
However the minerals follow a different path. A small amount stays liquefied underground, to solidify years later as deposits of lead, tin, and bismuth.
Another amount of minerals is superheated in the intense temperature, and either forms a gas or forms a solution with water and sulphur. The superheated matter is forced up through cracks in the crust and forms veins of minerals.
The rest of the minerals form mineral ore. The minerals that don't stay liquefied or superheat, they form solutions underground, and then crystallise when the solution cools down. These massive deposits are called hydrothermal deposits, and things like gold, silver and lead form here.
With a combined study of the Viking probes and of CNC meteorites which originated from Mars and stuck Earth, it has been conclusively proven that the following are confirmed to exist on Mars: Magnesium, Aluminium, Titanium, Iron, Chromium, Lithium, Cobalt, Nickel, Copper, Zinc, Niobium, Molybdenum, Lanthanum, Europium, Tungsten, and Gold. Breaking this long list down, we can see that a lot of these must have super-volcanic origins (niobium, gold, iron etc.). Furthermore, probes have detected bunches of hematite and nickel-iron on the surface of Mars. Whether these originated from volcanoes or not is unknown, but they can definitely be used to make steel.
So now that you know what all is on Mars, and where it came from, it's uses are up to us. For a new colony being established, the Iron and Titanium deposits will be of great interest, as they can be used as building materials on the colony. All the other resources will have their uses, from Neodymium in magnets to Gold in high-speed cables.
Mars is an unexplored land, and new discoveries are certain. But even now, with the information we have, we can conclusively say that there are essential minerals on Mars as a result of super-volcanic activity, and they would be useful to future colonists on the Red Planet.