In this article, you’ll get to know some commonly known evaporite rocks, as well as information about evaporite rocks to better understand them.
Evaporite Rocks Examples (Characteristics and Types)
Evaporites are beautiful chemical rocks with layers of crystalline minerals, created from particles found on the Earth’s surface.
As all bodies of water on the Earth’s surface contain dissolved salts, for minerals to form from these salts, the water must first evaporate in the atmosphere.
This allows the minerals that started as a solution to develop and turn solid.
These deposits then turn into the essential minerals that we know and use in today’s world.
The minerals included in evaporite rocks consist of:
Also included are various borates, silicates, nitrates, and sulfocarbonates.
Where Do Evaporite Mineral Rocks Grow?
An ideal environment for an evaporite to form needs to be almost entirely void of life.
This could be a small basin area or similar with a restricted inflow or outflow of water.
There also needs to be more water evaporating into the atmosphere within this area than arrives from rainfall, rivers, or streams.
The minerals to form the mixture need time to pool, settle, and marinate, kicking off the rock-forming process.
The Two Types of Evaporites
There are two different evaporite rocks. One type grows in a marine environment.
While the other type is classed as non-marine and grows in lakes.
Therefore, as they form in chemically different bodies of water, the minerals both types produce are also different.
So let’s dig further into their characteristics.
We usually find evaporite deposits in marine environments in coastal areas, such as lagoons and mudflats.
The seawater level that the rocks are growing in will determine the size of the mineral layers inside the stone.
The most common marine evaporite minerals are:
- Calcite – CaCO₃
- Calcite is a vital mineral that is found everywhere and is used as a construction material, soil treatment, construction aggregate, pigment, pharmaceutical, etc.
- Usually white, but can be colorless, grey, red, green, blue, yellow, brown, orange, or even black can occur when the mineral has impurities.
- Gypsum – CaSO4·2H2O
- Gypsum is often used in making insulation.
- Because of impurities, it is usually colorless, white, or tinted light brown, gray, yellow, green, or orange.
- Anhydrite – CaSO4
- Often used in plasters and cement as a drying agent.
- Sometimes, the color is bluish, blue-grey, violet, burgundy-red, white, rose-pink, brownish, reddish, grey, and dark grey.
- Halite – NaCl
- They frequently use this mineral for food preservation. For example, pieces can be ground in a salt mill or dusted over food with a shaker as finishing salt.
- The mineral is typically colorless or white but may also be light blue, dark blue, purple, pink, red, orange, yellow, or gray.
- Sylvite – KCI
- Perfect as a fertilizer. Colorless to white with shades of yellow and red because of inclusions.
- Carnallite – Cl3H12KMgO6
- Carnallite is often used in fertilizers.
- Colored yellow to white, reddish, and sometimes colorless or blue.
- Langbeinite – Mg2K2(SO4)3
- Langbeinite is a mineral made of essential nutrients for plants: potassium, magnesium, and sulfur. It is transparent, colorless, or white, with pale tints of yellow to green and violet crystalline masses.
- Poly Halite – Mg2K2(SO4)3
- Used as a fertilizer.
- Is typically colorless, white to gray. However, it may be brick red due to iron oxide inclusions.
- Kainite – KMG(SO4)
- Kainite is used as a natural form of potassium and magnesium, as a fertilizer, and as gritting salt.
- Dull is soft and colored white, yellowish, grey, reddish, or blue to violet.
- Kieserite – Mgso4
- Typically used in cropping, horticulture, market gardening, and maize production.
- Colorless, grayish-white, or yellowish.
These rocks are often called “saline lake deposits” and grow in lakes without an outlet—in arid and semiarid regions.
Such lakes form closed interior basins or shallow depressions on land where drainage is internal, and runoff does not reach the sea.
- A perennial lake – lakes which are there year-round.
- A playa lake – lakes that appear only during certain seasons.
- An area is like a lake that holds still water bodies intermittently or year-round.
Changing lake levels and water volumes can lead to fluctuating amounts of saline. Which can cause a different range and quantity of minerals to form.
Common minerals found in nonmarine deposits include:
- Blödite – Na2Mg(SO4)2•4(H2O)
- Biotite has several uses: a filler in paints, an additive to drilling muds, a filler and release agent in products made with rubber, and a non-stick coating on roofing shingles.
- Clear to yellow.
- Borax – Na₂[B₄O₅(OH)₄]·8H₂O
- The best-known use for borax is as a cleaner. While also used in many other household products, including toothpaste and mouthwashes. Cosmetics and paint and ceramic glaze.
- Translucent when fresh, but eventually turns opaque, developing a white powder on the surface.
- Epsomite – MgSO4·7H2O
- Used in its purified form, Epsomite is made into Epsom salts.
- Colorless to white with tints of yellow, green, and pink.
- Gaylussite – Na2Ca(CO3)2•5(H2O)
- Gaylussite is quite a rare mineral and a scarce gem.
- Greyish white.
- Glauberite – Na2Ca(SO4)2
- Used for dying, solar energy cells, and medicine.
- The color is ordinarily white, yellow, gray, or colorless.
- Mirabilite – Na2SO4·10H2O.
- Mirabilite is used for many conditions, such as constipation, red eyes, sore throats, and ulcers, and helps wounds heal.
- Colorless to white.
- Thenardite – Na2SO4
- Used in baking soda and also used in the glass and paper industries.
- Yellowish, reddish to gray-white prismatic crystals
- Trona – Na2CO3•NaHCO3•2H2O
- Used in producing glass, paper products, laundry detergents, and many other products.
- Colorless or white, grey-white, also grey to yellowish-grey, light yellow.
The Sedentary Family
Other rocks included in the sedentary family, but not created in water are:
- Clastic rocks from clay, silt, gravel, and boulders.
- They provide minerals, including clays, carbonates, sulfates, halides, zeolites, and chert.
- Coal forms from compressed plant particles.
- Minerals from coal include oxygen, aluminum, silicon, iron, sulfur, and calcium.
- Carbonate rocks comprise calcite and dolostone.
- Minerals include calcium carbonate, calcite and aragonite, and vaterite.
I hope this information has really opened up the world of evaporite deposits for you, and you have learned some interesting and helpful facts.
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