Minerals are natural resources needed as raw material for setup and extension of settlements on Mars. From recent unmanned missions some valuable minerals have been found in the regolith, most of them by the Mössbauer spectrometer MIMOS II. The atmospheric dust contains minerals, which allows atmospheric mining. The crust is enriched in iron. It is rich in chlorine, sulphur, potassium and phosphorus (as well as other volatile elements).
The most common elements making up Mars' crust are: silicon, oxygen, iron, magnesium, aluminum, calcium, & potassium. The elements sulphur, phosphorus, sodium, boron, chlorine, and bromine are needed for life and have been found on the planet.
Mars is fundamentally a igneous planet, made up of magma and minerals caused by the erosion of lava. These include plagioclase feldspar, pyroxenes and olivine (all basalt based minerals). Magnetite has been found. Opportunity found what is likely titanomagnetite (titanium rich magnetite).
In the presence of water, olivine gradually weathers into clays, which are common on Mars, especially in the northern low lands.
In the southern highlands, low calcium (ortho-) pyroxenes are present. These have a higher melting temperature, which suggests that the older highlands had higher temperature lavas than areas of more recent volcanism.
Intermediate and felsic rocks are present on Mars, but seem to be fairly rare. These include quartz rich dacites and granitoids which have been found by spacecraft in Syrtis Major and near the crater Antoniadi.
Curiosity found hydrated minerals, including calcium sulphate (gypsum).
Secondary minerals formed by water based weathering include: hematite, phyllosilicates (clay minerals), various carbonates (fairly rare), goethite, jaorsite, iron sulphite minerals, and opaline silica. (Thus, we may find opals on Mars.) Some of these minerals require acidic water, other need neutral or basic solutions. It is believed that carbonate formations are much more widespread, but buried.
Opportunity found a variety of sulphated minerals, thought to include: kieserite, sulphate anhydate, bassanite, hexahydrite, epsomite, jarosite, and gypsum. Salts including halite, bischofite, antarticite, bloedite, vanhoffite and glauberite are believed to be found. Jarosite is a mineral which can only form in water, which proved that Mars had liquid water (perhaps under a layer of surface ice) for long periods of time.
Silica has been found in the Columbia hills. This may have formed from acid vapours in the presence of water, as if it was in a hot spring.
Sedimentary formations are widespread, including sandstone.
A number of meteorites have been found on the Martian surface.
No minerals that are formed by life have been found on Mars, i.e. no amber, limestone, coral, petrochemicals, coal, marble, stromatolites, etc.
Detailed Descriptions of Particular Minerals:
Chemical formula: α-FeO(OH)
This mineral has been identified near the landing zones of the rovers Spirit and Opportunity, for example at "Columbia Hills". This mineral was probably created from iron under the influence of liquid water.
Chemical formula: α-Fe2O3
This mineral has been found at the landing zone of Opportunity. It is also suspected to be very common over the entire martian surface. Hematite is an iron ore, a source of Iron on Earth and is a major part of the Martian dust which is found planet wide.
Chemical formula: (Mg,Fe)2SiO4
This mineral has been found in Gusev Crater.
Calcium carbonate, magnesium, sodium, potassium, chloride and perchlorate have been found by the Phoenix lander (http://phoenix.lpl.arizona.edu/09_09_pr.php). Chloride, perhaps table salt, have also been found by Mars Odyssey.
// Wikipedia article on Mars Geology:
"The Geology of Mars: Evidence from Earth-Based Analogs", edited by Mary Chapman, ISBN 0-521-83292-6