Mineral-making hydrothermal waters are responsible for
formation of many deposits and mineral accumulations.
In spite of differences in mineral type and reserve
volume, association of these minerals has been all
formed by sedimentation of soluble materials in hot
waters. Location of this process has been rock pores
These hot waters are observable around igneous
intrusive massives by convection flow and sometimes
can be found in form of mineral-making springs on
However, magmatic waters have less important share in
formation of these kinds of waters. Most of these
waters’ origins are rain and subsurface waters and
also small amount of magmatic waters are added to this
Sometimes, penetrating waters meet cooling intrusive
massives or magma room of active and semi-active
volcanoes during their flow. Therefore, their
temperature and solubility increase. Magmatic waters
originating from surroundings of cooling massives are
added to the mentioned penetrating waters. After
warming process, these waters due to decrement of
specific gravity resulting from high temperature move
upward along with fractures and faults. On the way
upward, available minerals which are in the rocks will
assimilate minerals, such as lead, zinc, gold, copper,
With decrement of depth, the temperature and pressure
of this solution that is full of metallic cations also
decreases. This solution, in a special depth and
under certain factors, such as temperature and
pressure loses its minerals and moves downwards by
increment of specific gravity resulting from
re-cooling process. Thus, a cycle of warm water is
produced. In the side of this cycle located deeply in
the ground is solution and magmatic thermal dynamism
and in the other side is low temperature superficial
parts and sedimentation location. During formation of
a hydrothermal vein ore deposit, a couple of factors
have significant role which are; heat source,
appropriate network of fractures, suitability of
solution chemical compounds and rocks located on the
way upward plus sufficiency of surface and subsurface
waters up to level required for efficient cycle. From
the mentioned points, it is inferred that there is a
straightforward function between mineralogical
composition of hydro thermal ore deposits and rocks
located on the way of hydrothermal cycle plus water
temperature. For instance, uranium-bearing ore
deposits are formed in acidic igneous rocks and
hydrothermal silver ore deposits in andesites plus
The most important hydrothermal ore deposits are asfollows;
Gold, silver, mercury, antimony, fluorite, barite,
lead, zinc, alunite, kaolinite, magnesite, uranium andcopper.
Vein-form mercury ore deposits
Mercury is in form of cynnaber in nature. This
mineral is formed in low depth up to surface ofground.
The temperature of its formation varies
between 50 to 200C. At present, cynnaber is forming
in the hot water springs of New Zealand and western
part of the United States. There is no hesitation
that mercury mineralisation within different periods
of time, but due to unstability of mercury and its
compounds go under various changing processes.
Mercury hydrothermal mineralistion is often with
antimony. Stibnite is the most important accessory
mineral to cynnaber in hydrothermal veins.
Hydrothermal gold ore deposits
Vein-form gold ore deposits are found in volcanic and
metamorphosed sedimentary rocks. In these ore
deposits, gold can be found with sulfides, arsenides
and seldom are found freely. The amount of reserves
has been less than one million ton and the gold carat
is more 5gr/ton in exploitable veins. Gold veins are
formed in 800m from ground surface. The temperature
of its formation is at 50 to 200C. Vein-form ore
deposits have been found in Canada, Rhodesia and
Vein-form lead and zinc ore deposits
Lead and zinc ore deposits are relatively abundant.
They are mostly in vast volcanic belts of the western
USA, Japan, the Philippines, Iran and the Alps. The
most important minerals of this reserve are;
sphalerite, galena and chalcopyrite. Sometimes galena
