Evaporite deposits

Evaporite Deposits
A short series of lectures prepared for the
third level of Geology, Tanta University
by
Hassan Z. Harraz
hharraz2006@yahoo.com
@Hassan Z. Harraz
Evaporite Deposits

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Evaporite Deposits

DEFINATION
Evaporite mineral:
 is a mineral sediment (i.e. chemical sediment)
that result originally precipitated from saline
(brine) solutions concentrated and crystallization
by solar evaporation from an aqueous solution.
Considered as Inorganic/Chemical
Sedimentary Rock types:
“Chemical”: derived from the precipitation of
dissolved minerals in water.
“Inorganic”: minerals precipitate because of
evaporation and/or chemical activity.
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Evaporite Deposits
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Evaporite (or Salt) deposits
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Evaporite Deposits
 that are composed of minerals that originally precipitated from saline (brine)
solutions concentrated by solar evaporation.
Most evaporites are derived from bodies of Sea-water, but under special
conditions, Inland lakes may also give rise to evaporite deposits, particularly in
regions of low rainfall and high temperature.
 Evaporite deposits are excellent indicators of paleoclimate (need a hot and
arid climate for major evaporite deposits to form)
 The original character of most evaporite deposits has been destroyed by
replacement through circulating fluids through geologic time
 Evaporite deposits are known from all the continents,
 Ages: ranging from Precambrian to Recent
 Precambrian evaporite deposits are scarces, either because:
 they were not deposits
 they have been dissolved away during diagenesis through geologic time.
 The greatest evaporite deposits are formed during Permian and Miocene
periods.
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 Minerals precipitated from “super-saturated” saline water in enclosed
basin environments under dry arid conditions with high evaporation
rates (e.g., playa lakes).
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Deposition of minerals by evaporation is dependent on factors:
1) Solubility contents,
2) Temperature,
3) Pressure,
4) Depositional environment, and
5) Seasonal and climatic changes .
PROCESS OF MINERAL FORMATION BY EVAPORATION
Requirements
 Arid Environment, High
Temperature
 Low Humidity
 little replenishment from open
ocean, or streams
Rates of Evaporite Deposition
 Rates of evaporite deposition are
FAST (compared to other sediments)
 Subaqueous evaporites may be
deposited at rates exceeding 10
cm/yr!! …(Compare this to
mm/1000 yr for most sediments).
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1) Chemistry of Seawater
Dissolved Species - Seawater
 About 3.45% of seawater consists of dissolved
salts of which 99.7% by weight is made up of
only seven, ions that are as listed below :-
 Most common ions: Cl-, Na+, Mg 2+, SO4
2-, Ca2+,
K+...
 Trace components: Br, F, B, Sr
85.65 % Na2+ and Cl- ions
NaCl is most abundant because of
composition of seawater:
remaining solutes 14.35%
Na+ 30.61 Cl- 55.04
Mg2+ 3.69 SO4
2- 7.68
Ca2+ 1.16 HCO3- 0.41
K+ 1.10
CHEMISTRY OF EVAPORITES
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 In terms of volumes of precipitated salts, experiments like that show that
if a column of sea water 1000 m (1 km) thick is evaporated to dryness,
the precipitated salt (evaporite) deposits would be about 17 m thick.
 1000 m (1 km) of seawater will
produce 17 m of evaporites:
 0.1 m would be CaCO3
 0.6 m would be gypsum
(CaSO4.2H2O),
 13.3 m would be halite (NaCl), and
 the rest, 3.0 m, would be mainly
salts of potassium and magnesium
(KCl, KMgCl).
Volumes of precipitated salts
 Note:
ppt. sequence controlled by
solubility – least soluble first:
least soluble
High soluble
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Extracted and produced by
i) Surface Mining
ii) Underground Mining
iii) Solution mining
1) Burried Evaporite deposits :
Natural
Ancient Evaporite deposits
Evaporite deposits that formed during
various warming Seasonal and
climatic change periods of geologic
times.
Like: Shallow basin with high rate of
evaporation – Gulf of Mexico, Persian
Gulf, Ancient Mediterranean Sea, Red
Sea
2) Brine Evaporite deposits:
 Natural and synthetic
Evaporite deposits that formed today
from evaporation:
 Ocean and Sea water
 Saline Lakes water
 Inland Lakes water
Extracted and produced by
Solar evaporation in:
 Pond
Marsh
Evaporite Deposits
 Playa lake basins
(are formed between
mountain ranges, collected)
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ENVIRONMENTS FOR EVAPORITE PRECIPITATION
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Evaporite Deposits
 Brine evaporite deposits
 Found in both Marine and Continental environments
Environments
Marine:
Coastal zone
Mud flats –
Sabkhas
Salt pans
Barried basins
Continental:
 Salt/Saline lakes
 Springs
 Groundwater
There are two types of evaporate deposits:
1) Marine evaporites: which can also be described as ocean or sea water
deposits (solutions derived from normal sea water by evaporation are said to
be hypersaline), and
2) Continental evaporites: which are found in standing bodies of water such
as Inland lakes; also groundwater.
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i) Marine Evaporite Deposits
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Coastal Salt Pans

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Mixed Salt Minerals

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Coastal Beach salts

i) Marine Evaporite Deposits
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Salt deposits were formed during the “Messinian Salinity Crisis”, a geological event during
which the Mediterranean Sea was cut off from the Atlantic Ocean and dried up (or
mostly dried up), creating massive deposits of previously dissolved salts.
This occurred at the end of the Messinian age ( from 5.96 to 5.33 Ma ago ) of the
Miocene epoch, ending when the Atlantic again flowed into the basin
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Evaporite Deposits

Volume of
water
remaining
Evaporite Precipitated
50%
At this point, minor carbonates
(CaCO3 and MgCO3 ) arebegin to
form.
A little iron oxide (Siderite) and some
aragonite are precipitated.
Minor quantities of carbonate
minerals (Calcite and dolomite) form.
a) Calcite(CaCO3):
 Precipitates if < 50% of seawater is removed.
 Only accounts for a small % of the total solids
20%
Gypsum precipitates:
Gypsum (<42°C) or Anhydrite (>42°C).
b) Gypsum:
 Precipitates if 80-90% of seawater has been removed
 Solution is denser
10% Rock salt (halite) precipitates
c) Halite:
 Precipitates if 86-94% of original seawater has been
removed
 Brine (solution) is very dense
 The deposition of salt beds provides the source for about
three-fourths of all salt used.
5%
Mg & K salts precipitate
Precipitation of various
magnesium sulfates [Kieserite
(MgSO4) and chlorides(MgCl2),
and finally to NaBr and KCl.
Potassium and Magnesium salts
(Kainite (KMg(SO4)Cl * 3H2O),
Carnallite (KMgCl3*6H2O),
Sylvite(KCl))
d) Potassic salts:
 Precipitate if > 94 % of original seawater has been
removed
 So: ionic strength (potential) of evaporating seawater has
a strong control over minerals that form.
 After the deposition of common salt, chlorides and sulfates of
magnesium and potassium are the other chief salts deposited.
The potassium minerals result from evaporation carried
almost to completion and, therefore, only rarely are they
deposited.
2) Evaporation Sequence of Seawater
IncreasingEvaporationRates
The first phase
Decreasingorderofsolubility
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Calcium Carbonate Deposits

Jashak salt dome, Iran
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Rock salt crust mined from the lake bed
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ii) Continental and Inland lakes Evaporite Deposits
 Examples of modern continental depositional environments include the Great Salt Lake in
Utah and the Dead Sea, which lies between Jordan and Israel.
 These deposits also may contain important minerals that help in today's economy.
 Continental evaporite deposits often help to paint a picture into past Earth climates:
Some particular deposits even show important tectonic and climatic changes.
 Primary examples of this are called “Saline lake deposits".
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Saline Inland lakes:
Salt lakes
Alkali (or Soda) Lakes
Playa lakes; which are lakes that appear
only during certain seasons,
Perennial lakes: , which are lakes
that are there year-round
Bitter (or Sulfate) Lakes
Potash Lakes
Borate Lakes
Groundwater
Hot Springs

Salt
Geode…Continental
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Order of precipitation of common compounds in Continental waters
(saline lakes) and Inland Brine Lakes evaporation:
1) CaCO3 and MgCO3 are the 1st to precipitate
2) CaSO4 precipitates …. All calcium are precipitated ( Leaving mostly Na
and Mg cations)
3) NaCO3 are precipitated next as:
3.1) Borax (Na2B4O7·10H2O or Na2[B4O5(OH)4]·8H2O)
3.2) Borates
3.3) Nitrates
3.4) Natron (Na2CO2.10H2O)
3.5) Trona (NaHCO3.Na2CO3.2H2O)
4) NaSO4 are precipitated
5) MgSO4 and Epsomite/ Epsom salts (MgSO4.7H2O) precipitated ….. left
NaCl
6) NaCl saltern is left. These are fairly common (Great Salt Lake)
7) MgCl2 and CaCl2 lakes are precipitated
Precipitationsequence
EVAPORATION SEQUENCE OF CONTINENTAL WATERS (Saline Lakes)
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Figure 5.25 (a) Schematic cross section showing the important features necessary for the formation of large marine
evaporite sequences. (b) Paragenetic sequence for an evaporite assemblage from typical sea water containing the
ingredients shown in the left hand column. The amount of sea water (per 1000 liter volume) that has to evaporate in order
to consecutively precipitate the observed sequence of mineral salts is shown by the curve adjacent to the paragenetic
sequence (diagrams modified after Guilbert and Park, 1986).
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Kind of Inland Lakes
1) Saline Lakes:
i) Salt Lakes: rich in sodium chloride (NaCl)
ii) Alkali (or Soda) Lakes: rich in sodium carbonate (Na2CO3)
Soda lakes have enormous phytoplankton populations not
so with other sodium rich lakes.
iii) Perennial lakes, which are lakes that are there year-round; or
iv) Playa lakes, which are lakes that appear only during certain
seasons.
2) Bitter (or Sulfate) Lakes: rich in sodium sulfate (Na2SO4)
3) Potash Lakes
4) Borate Lakes
DEPOSITION FROM INLAND LAKES
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Playa lake basins
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Evaporite Deposits
 are formed between mountain ranges,
 are lakes that appear only during certain season,
 Called Salt Playas,
 on salt Playas, desert winds distribute sands and silt, upon which later salts may be
deposited during subsequent lake periods.
 This also gives alternations of salines with sand, clay and minor calcium
carbonate.
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1) Deposition from Salt Lakes
 The deposits formed from the evaporation of salt lakes are similar to
those obtained from ocean water.
 The relatively small size of lakes, however, makes them more
responsive to climate changes, with the result that they exhibit
greater fluctuations of deposition.
 Evaporites formed during periods of desiccation may be re-dissolved
during subsequent periods of scansion.
 Moreover, lakes constantly receive new supplies of fresh water, salts,
and also sediments.
 The resulting saline deposits, therefore, are generally thin-bedded
alternations of impure salts and clays.
 Also, on salt Playas, desert winds distribute sands and silt, upon
which later salts may be deposited during subsequent lake periods.
 This also gives alternations of salines with sand, clay and minor
calcium carbonate.
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Salton Sea California
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2) Deposition from Alkali (or Soda) Lakes
 Alkali (or Soda) lakes is lake rich in sodium compounds.
 In alkali or soda lakes sodium carbonate predominates, potassium
carbonate may be abundant, and common salt is always present.
Source materials: Most of the sodium carbonate has been derived directly
by decomposition of volcanic rocks, but some is also formed by slow and
complex chemical reactions with other sodium and calcium salts; it may
be formed also by the action of algae on sodium sulfate.
The potassium carbonate is considered to be the indirect product of the
work of organisms.
Example: Owens and Mono Lakes in California, the Soda Lakes of Nevada,
and the Natron Lakes of Egypt.
The Natron Lakes of Egypt are alternately wet and dry, and evaporation
leaves a layer of natron and salt, bordered by sodium carbonate.
Note:
In arid regions- precipitates of carbonate combined with
sodium are found commonly called natron and trona
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3) Deposition from Bitter (or Sulfate ) Lakes
Bitternresults when water evaporates and most salts have
crystalized and precipitated The liquid that remains is called
Bittern
 In bitter lakes, contains sodium sulfate predominates,
bromides and magnesium salts…. but carbonate and chloride are
present.
 Source materials: The sulfate may be derived from the
decomposition of rocks that contain sulfates, or from the
leaching of buried beds of sulfates.
 Such lakes are common in the Arid Regions of America and
Asia.
 Examples are Verde Valley Lake in Arizona; Soda and
Searles Lakes in California; and numerous lakes in New
Mexico; Lakes Altai and Domoshakovo in Russia.
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4) Deposition from Potash Lakes
Potassium
4th ranking cation
High potassium levels are lethal to many aquatic
animals
Source of potassium
 The potash is believed to have come from the
surrounding country that formerly was burred
over by the Indians, releasing plant ashes.
Potash potassium carbonate (K2CO3)
Thought to be ashes of ancient fires
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1.3) Potash Deposition
After the deposition of common salt, chlorides and sulfates of magnesium and
potassium are the other chief salts deposited. The potassium minerals result from
evaporation carried almost to completion and, therefore, only rarely are they
deposited.
The famous Stassfurt deposits of Germany represent the only complete sequence of
deposition of oceanic salts.
Economic sources …
 Sedimentary salt beds remaining from ancient inland seas (evaporite deposits)
 Salt lakes and natural brines
 The world has an estimated 250 billion metric tons of K2O resources.
Potash refers to a variety of K-bearing minerals
There, some 30 saline minerals are known
Potash deposits, i.e. natural concentrations of raw potash, consist of potassium salt
rock, predominantly made up of the potassium minerals:
 Sylvite (KCl),
 Carnallite (KMgCl3*6H2O),
 Kainite (4KCl.4MgSO4.11H2O) and
 Langbeinite (K2Mg2(SO4)3)
The formation of the potash deposits (Barrier theory“)
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World Potash Mine Production 2003
0
1
2
3
4
5
6
7
8
9
10
Canada
Russia
Belarus
Germ
any
Israel
Jordan
United
States
United
Kingdom
Spain
China
Chile
Brazil
Ukraine
Millionmetrictons,K2O
Source: IFA
%oftotalproduction
78% of total K2O produced
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17
15
13
0
5
10
15
20
25
30
35
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Potash Deposits in Dead Sea
 K extracted from Dead Sea
 The world’s largest reserve of potash in
the form of salt solutions is the Dead Sea
(up to 1 billion tonnes of K2O), which has
been used for potash production since the
beginning of the 1930s.
 contains an estimated up to 1 billion
tonnes KCl
 Israel and Jordon represented 11% of
world production in 2003
 Today DSW operates on the Israeli side
and APC on the Jordanian side
 Arab Potash, the only producer in Jordan
is being privatized
 Dead Sea Works (DSW), with production
in Israel and recent acquisitions in Spain
and UK is the world’s 5th largest producer
 Bromine is remarkably concentrated in
the Dead Sea to the extent of 0.4%
compared with 0.0064 % in ocean water.
K2Oproduction,‘000t
0
500
1000
1500
2000
2500
1994 1996 1998 2000 2002
Israel Jordan
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5) Deposition from Borate Lakes
 Source materials: The borax of
the lakes is considered to have been
leached from, surrounding igneous
rocks or to have been contributed
by magmatic hot springs.
Mineralogy: The chief boron
minerals of playas and brines are:
 Borax (Na2B4O7.10H2O)
 Colemanite (Ca2B6O11.5H2O)
 Ulexite (Na2.2CaO.5B2O3.16H2O)
 Searlesite
(3Na2O.B2O3.4SiO2.2H2O) is also
found at Searles Marsh
Magnesium borates are considered to be typical of marine conditions and calcium borates of lake-bod
deposits.
Most borates of commerceare obtained from lakes, lake-bed deposits,or dry lakes.
Borate lakes are relatively uncommon, but several are known in California, Nevada, Oregon, Tibet, Argentina,
Chile, and Bolivia.
Borax and other boron-containing minerals are mined from evaporite lake deposits in Death Valley and
Searled and Borax Lakes, all in California; and in Argentina, Bolivia, Turkey, and China.
Formerly, most of the borax in the United States was obtained from lake waters in California and Nevada or
from playas.
Subsequently, borax was made less expensively from colemaniteand ulexite, and later from kernite. At
present, the only lakes yielding commercialborax are Searles and Owens, in California, where it is extracted
in conjunction with other salts.
Uses:
Borax has a wide variety of uses. It is a component of many
detergents, cosmetics, and enamel glazes. It is also used to make
buffer solutions in biochemistry, as a fire retardant, as an anti-
fungal compound for fiberglass, as an insecticide, as a flux in
metallurgy, and as a precursor for other boron compounds.
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Borate and Bromine Deposition
Minor quantities of borates and bromine are obtained from
marine salts. Although borates are mostly formed under other
conditions, some are precipitated along with potassium
minerals from marine residual liquids.
Bromine is also deposited from residual liquids of seawater.
The carnallite of Stassfurt contains 0.2 % bromine, which is
extracted in Germany during the refining of the potash salts.
Bromine is remarkably concentrated in the Dead Sea to the
extent of 0.4% compared with 0.0064 % in ocean water.
Most bromine, however, is a by-product of salt, from salt
brines and seawater.
 Example: Boracite and other borates occur in the potash salt
of Germany in association with carnallite and the overlying
potash minerals.
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Compared between Marine and Continental evaporites
Marine evaporites Continental evaporites
 Marine Environments:
 Coastal
 Mud flats – Sabkhas
 Salt pans
 Barried basins
 can be described as ocean or sea water deposits
(solutions derived from normal sea water by evaporation
are said to be hypersaline)
 Shallow basin with high rate of evaporation: e.g. Gulf of
Mexico, Persian Gulf, ancient Mediterranean Sea, and
Red Sea.
 Marine evaporites tend to have thicker deposits.
 Marine evaporite deposits are widespread.
 In North America, for example, strata of marine
evaporites underlie as much as 30% of the land
area.
 The most important salts that precipitate from sea water:
Gypsum, Halite, and Potash salts {Sylvite (KCl),
Carnallite (KMgCl3 * 6H2O), Langbeinite
(K2Mg2(SO4)3), Polyhalite (K2Ca2Mg(SO4)6 * H2O),
Kanite (KMg(SO4)Cl * 3H2O), and Kieserite (MgSO4)}
 Huge marine evaporite deposits were laid down in the
Seas and oceans during the Permian and Miocene
Epochs.
 Marine evaporites produce:
 Most of the salt that we use.
 The gypsum used for plaster.
 Continental Environments:
 Saline Inland lakes:
 Salt lakes
 Alkali (or Soda) Lakes
 Playa lakes
 Perennial lakes
 Bitter (or Sulfate) Lakes
 Potash Lakes
 Borate Lakes
 Groundwater
 Springs
 The layers of salts precipitate as a consequence of evaporation:
 Salts that precipitate from lake water of suitable
composition include: Sodium carbonate (Na2CO3), Sodium
sulfate (Na2SO4), and Borax (Na2B4O7.1OH2O).
 The most important salts that precipitate from lake: Blödite, Borax
(Na2B4O7.1OH2O), Epsomite (MgSO4.7H2O), Gaylussite,
Glauberite, Mirabilite, Thenardite and Trona
(NaHCO3.Na2CO3.2H2O).
 Continental deposits may also contain Halite, Gypsum, and
Anhydrite, and may in some cases even be dominated by these
minerals.
 Huge evaporite deposits of Sodium carbonate were laid down in
the Green River basin of Wyoming during the Eocene Epoch.
Oil shales were also deposited in the basin.
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Lakes Seawater
1) CalciteCaCO3 and Magnesite (MgCO3 ) 1) Calcite(CaCO3) and Dolomite (CaMg(CO3 )2
2) CaSO4 precipitates next. 2) Gypsum:
Gypsum precipitates:
Gypsum (<42°C) or Anhydrite (>42°C).
3) NaCO3 precipitates next as:
3.1) Borax (Na2B4O7·10H2O or
Na2[B4O5(OH)4]·8H2O)
3.2) Borates
3.3) Nitrates
3.4) Natron (Na2CO2.10H2O)
3.5) Trona (NaHCO3.Na2CO3.2H2O)
4) NaSO4 precipitates
5) MgSO4 and Epsomite/ Epsom salts
(MgSO4.7H2O) precipitates
3) Halite:
 Precipitates if 86-94% of original seawater
has been removed
 Brine (solution) is very dense
6) NaCl saltern is left. These are fairly
common (Great Salt Lake)
7) MgCl2 and CaCl2 are precipitates
4) Potassic salts:
 Precipitate if > 94 % of original seawater
has been removed
 So: ionic strength (potential) of
evaporating seawater has a strong control
over minerals that form
Compared between Evaporation Sequence of Seawater and Lakes
IncreasingEvaporationRates
Decreasingorderofsolubility
The
first
phase
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Calcium Sulfate Deposition
Calcium sulfate may be deposited either in
the form of gypsum Gypsum (<42°C) or
anhydrite (>42°C), depending upon the
temperature, pressure, and salinity of the
solution.
When the water has been evaporated to
about 70% of its original volume, calcium
sulfate starts to separate. At the
temperatures of evaporation of marine
basins, much gypsum will always be
deposited first if the temperature is <42°C,
and that marine beds of pure anhydrite
imply either that the early deposited
gypsum was converted to anhydrite or that
deposition occurred above the conversion
temperature of >42°C.
 Equilibrium temperature for the reaction
CaSO4*2H2O CaSO4 + 2H2O(Liq. Sol.)
is a function of activity of H2O of the
solution.
 Anhydrite can be hydrated back to
gypsum upon uplift and exposure to low-
salinity surface waters.
Resulting Products.
 Calcium sulfate deposition occurs in:
1) Beds of relatively pure gypsum or
anhydrite from a few meters to
many hundreds of meters in
thickness (gypsum beds
constitute one of the most
important nonmetallic resources
and anhydrite finds little use);
2) Gypsum beds with impurities of
anhydrite;
3) Alabaster, a softer and lighter
variety of gypsum; and
4) Gypsite, an admixture with dirt.
5) The beds are generally
interstratified with limestone or
shale, and they are commonly
associated with salt.
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Economic importance of evaporites
Evaporites are important economically because of
their mineralogy, their physical properties in-situ,
and their behaviour within the subsurface.
Evaporite minerals, especially nitrate minerals, are
economically important in Peru and Chile. Nitrate
minerals are often mined for use in the production
on fertilizer and explosives.
Thick halite deposits are expected to become an
important location for the disposal of nuclear
waste because of their geologic stability,
predictable engineering and physical behaviour,
and imperviousness to groundwater.
Salt Domes: salt formations are famous for their
ability to form diapirs, which produce ideal
locations for trapping petroleum deposits.
 Evaporite minerals start to precipitate when their concentration in water reaches
such a level that they can no longer exist as solutes.
 The minerals precipitate out of solution in the reverse order of their solubilities,
such that the order of precipitation from sea water is
 Calcite (CaCO3) and dolomite (CaMg(CO3)2)
 Gypsum(CaSO4-2H2O) and anhydrite (CaSO4).
 Halite (i.e. common salt, NaCl)
 Potassium and magnesium salts
 The abundance of rocksformed by seawater precipitation is in the same order
as the precipitation given above. Thus, limestone (calcite) and dolomite are
more common than gypsum, which is more common than halite, which is
more common than potassium and magnesium salts.
 Evaporites can also be easily recrystallized in laboratories in order to investigate
the onditions and characteristics of their formation.
Major groups of evaporite minerals
More than eighty naturally occurring evaporite minerals have
been identified. The intricate equilibrium relationships among these
minerals have been the subject of many studies over the years. This
is a chart that shows minerals that form the marine
evaporite rocks, they are usually the most common
minerals that appear in this kind of deposit.
Hanksite, Na22K(SO4)9(CO3)2Cl, one of the few
minerals that is both a carbonate and a sulfate
Mineral class
Mineral
name
ChemicalComposition Rock name
Halites
(or
Chlorides)
Halite NaCl Halite; rock-salt
Sylvite KCl
Potash Salts
Carnallite KMgCl3 * 6H2O
Kainite KMg(SO4)Cl * 3H2O
Sulfates
Polyhalite K2Ca2Mg(SO4)6 * H2O
Langbeinite K2Mg2(SO4)3
Anhydrate CaSO4 Anhydrate
Gypsum CaSO4 * 2H2O Gypsum
Kieserite MgSO4 * H2O --
Carbonates
Dolomite CaMg(CO3)2 Dolomite, Dolostone
Calcite CaCO3 Limestone
Magnesite MgCO3 --
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Salt Extraction Technologies
Today, there are four methods used to produce dry salt based on the method of recovery :
(a) Surface Mining
(b) Underground mining: Also known as rock salt mining, this process involves conventional
mining of the underground deposits through drilling and blasting whereby solid rock salt is
removed. Mining is carried out at depths between 100 m to more than 1500 m below the
surface.
(c) Solution mining: Evaporated or refined salt is produced through solution mining of
underground deposits. The saline brine is pumped to the surface where water is evaporated
using mechanical means such as steam-powered multiple effect or electric powered vapour
compression evaporators. In the process, a thick slurry of brine and salt crystals is formed.
(d) Solar evaporation method (Normal evaporation): This method involves extraction of salt
from oceans and saline water bodies by evaporation of water in solar ponds leaving salt crystals
which are then harvested using mechanical means. Solar and wind energy is used in the
evaporation process. The method is used in regions where the evaporation rate exceeds the
precipitation rate.
More than one third of the salt production worldwide is produced by solar evaporation of sea water or
inland brines (Sedivy, 2009). In the salt crystallization plants, saturated brine or rock salt and solar salt
can be used as a raw material for the process. A summary of the possible process routes for the
production of crystallized salt based on rock salt deposits is shown in Fig.2. Processes that are used
in the production of vacuum salt from sea water or lake brine as a raw material are shown in Fig.3.
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1) Technology of the Salt (NaCl) Production
Fig.2. Processes for production of crystallized salt based on rock salt deposits (Westphal et al., 2010)
Underground mining
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i) Surface Mining
iii) Solution mining:
 two wells
 selective dissolution
 hot leaching
well
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Obtain common salt from Sea water
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Evaporite Deposits

Getting salt from rock salt
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Evaporite Deposits

1) Technology of the Salt (NaCl) Production
Fig.3. Processes for salt production from brine (Westphal et al., 2010)
Solar evaporation method
(Normal evaporation):
 Pond
 Marsh
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Brines form by strong evaporation.
These ponds on the shores of Great
Salt Lake are sources of magnesium
as well as salt.
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50

Clean washing salt
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Types of Salt
Finely ground powders and coarse, irregular chunks in rainbow hues – deep, crystalline
black, iron red, rose pink, fire red and sea grey.
1) TABLE SALT
2) KOSHER SALT
3) SEA SALT
4) HIMALAYAN PINK SALT
5) CELTIC SEA SALT
6) FLEUR DE SEL
7) KALA NAMAK
8) FLAKE SALT
9) BLACK HAWAIIAN SALT
10) RED HAWAIIAN SALT
11) SMOKED SALT
12) PICKLING SALT
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Calcium Carbonate Deposits
 Calcium and magnesium carbonate give rise to deposits of
limestones, dolomite, and magnesite.
 Calcium Carbonate Deposits may be of:
i) Chemical/inorganic origin (by evaporation)
ii) Organic/biogenic origin (by organism)
 Calcium Carbonate Deposits are the most common type of
Chemical/inorganic sediment forming today by evaporation
process as well as Organic/biogenic origins.
 Calcium Carbonate Deposits are formed by
i) evaporation process (chemical precipitation/ usually fine
grained)
ii) Organic/biogenic origin (grain size depending upon type of
organism).
 Calcium Carbonate Deposits may be formed from:
i) Marine saline water (sea and ocean, lakes, inland lakes) .
ii) Marine fresh water origin
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Inorganic/Chemical Sediments
Oolitic Limestone:
Ooliths/ooids and Pisoliths
Limestone is precipitated
directly from seawater.

Evaporite deposits

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