The key difference between potash and polyhalite is that the term potash refers to the mineral salts containing potassium, whereas the term polyhalite refers to the hydrated sulfate mineral having potassium, calcium and magnesium ions.
Potash and polyhalite are mineral compounds we can find in nature. Both these are water-soluble minerals and are very useful as fertilizers. They have different methods of production and different structures as well.
CONTENTS
1. Overview and Key Difference
2. What is Potash
3. What is Polyhalite
4. Side by Side Comparison – Potash vs Polyhalite in Tabular Form
5. Summary
What is Potash?
Potash is a water-soluble mineral containing potassium ions. This compound is produced worldwide in very large amounts to be used as a fertilizer. The natural sources of potash come from natural evaporate deposits.
Figure 01: Appearance of Potash
Often, these ores are buried deep down the earth. These ores are rich in potassium chloride (KCl), sodium chloride (NaCl) and some other salts along with clay. We can obtain this mineral via mining. Another method is to dissolve the ore prior to mining and evaporate. In this evaporation method, we can inject hot water into the potash, dissolving the mineral. Then we can pump it onto the surface. Thereafter, we can concentrate the potash via solar evaporation.
After nitrogen and phosphorous, potassium is the most wanted nutrient for crops. It is used as a soil fertilizer. Potash can improve the water retention in soil, can increase the yield, and increase the nutrient value, taste, intensity, texture of the outcome of the crop. In addition, it is useful as a component in aluminum recycling, production of potassium hydroxide, and metal electroplating.
What is Polyhalite?
Polyhalite is a water-soluble mineral having potassium, calcium and magnesium ions. It is an evaporite mineral that has hydrated sulfates. The chemical formula for this mineral can be given as K2Ca2Mg(SO4)4·2H2O. These minerals have a triclinic crystal structure, but the crystal form is very rare. Usually, this mineral can be found in massive to fibrous form. Typically, it is colorless, but there can be a pink coloration as well. When considering the occurrence, it occurs in sedimentary marine evaporates.
Figure 02: Appearance of Polyhalite
There are four important nutrients we can obtain from the polyhalite mineral: sulfate, sulfate of potash, magnesium sulfate and calcium sulfate. It is a brittle mineral that has a conchoidal fracture. Furthermore, it has a vitreous, resinous luster. The mineral streak of polyhalite is white. It is a transparent mineral.
What is the Difference Between Potash and Polyhalite?
Both, potash and polyhalite, are water-soluble minerals that are useful as fertilizers. However, the key difference between potash and polyhalite is that the term potash refers to the mineral salts containing potassium, whereas the term polyhalite refers to the hydrated sulfate mineral having potassium, calcium and magnesium ions. Moreover, potash is a mineral containing simple halides of potassium and sodium with trace salts and clay while polyhalite is a mineral containing sulfates of potassium, calcium, and magnesium. When considering the production process, we can obtain potash via mining, dissolution or evaporation. Meanwhile, we can obtain polyhalite from mining sedimentary marine evaporates. A visible difference between potash and polyhalite is their color. Potash appears in a brick red color, whereas polyhalite appears colorless with pink coloration.
Summary – Potash vs Polyhalite
Potash and polyhalite are water-soluble minerals that are useful as fertilizers. The key difference between potash and polyhalite is that the term potash refers to the mineral salts containing potassium, whereas the term polyhalite refers to the hydrated sulfate mineral having potassium, calcium and magnesium ions.
Reference:
1. “Potash.” Wikipedia, Wikimedia Foundation, 26 Nov. 2019, Available here.
2. “Polyhalite.” Wikipedia, Wikimedia Foundation, 11 Nov. 2019, Available here.
Image Courtesy:
1. “PotashUSGOV” – English Wikipedia, original upload 3 August 2004 by Chris 73 (Public Domain) via Commons Wikimedia
2. “History museum of Truskavets 081” By Andrew Butko (CC BY-SA 3.0) via Commons Wikimedia
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