Deposit formation is a complicated phenomenon. In order to understand it, it is necessary to find answers to many questions as: what is deposit, mineral, where to find the source of the ore matter, what are geological processes that result in deposit and accumulation of valuable component in ore. There are five ages in geological record of ore formation in the territory of the Khibiny area: Upper Archean- oldest 2.6 billion years, Low Proterozoic - 2.6-1.9 billion years, Middle Proterozoic - 1.9-1.6 billion years, Paleozoic - 570-230 billion years and Caenozoic - less than 67 billion years. Different minerals formed during each of these epochs, conditions of mineral formations were different.
Minerals are mined using two methods: underground and open-pit mining, but at present open-pit mining is decreasing. Soon all mining in the Kola peninsula will go deep underground. It should be noted that territory of the Khibiny massif there are about 500 types of minerals. Such a great number of natural resources including minerals can't be found anywhere on the Earth. More than two dozens of minerals are of practical value, a hundred of minerals are second to none.
As ores are valuable rocks, formation conditions should be studied in close relation to history of the Earth crust development. There are three types of minerals by formation: sedimentary, magmatic and metamorphic. The oldest natural resources of Murmansk region are ferruginous quartzite of Olenegorsk group of deposits. Its age is about 3 billion years. Many geologists believe that ore minerals - magnetite, hematite and quartz were accumulated as sediments at the bottom of the ancient sea that existed during Archean age, i.e. had primary sedimentary origin. As a result of long-term fault of continental rocks under the action of three elements - water, wind and sun, they bore iron and silica that were sedimented at the sea bottom.
The evidence is a banded structure of layers resembling layer-cake: bands of ore minerals are interchanging with quartz bands. Accumulated ore matter mass areas were going deep under the Earth crust where they were exposed to metamorphism, i.e. high temperature and pressure. For many hundred billion years, ore layers were tightly cemented, crystallized and were even moved and inverted.
Being horizontal during ore sedimentation, they were inclined under different angles later. Now we observed them as is.
However, there are other explanations of ferruginous quartzite origin. Some geologists believe that iron and silica accumulation at the sea bottom is connected to deep sea eruptions, and then ore matter was subjected to metamorphism. There was a extra-terrestrial hypothesis of iron sedimentation out of stardust. It is well-known, for instance, that dust-like nebula of the Milky Way consists of iron particles. Our planet coming through this nebula acted as a magnet of iron particles that were the ore matter source, silica was formed together with iron out of earth rocks. This explanation is open to questions. The point is that nickel together with iron should come from outer space to the Earth as it is found in all iron meteorites. However, there are no nickel minerals in ferruginous quartzite.