Feldspar Uses

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What are its Uses?

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Feldspar is a common raw material that is used in the process of glassmaking, ceramics, and to an extent as a filler and as an extender in the paint, plastics, and rubber industries. In glassmaking, alumina from feldspar actually improves the product’s hardness, durability, and resistance against chemical corrosion. In ceramics, the alkalis in feldspar are calcium oxide, potassium oxide, and sodium oxide. All of these act as a flux that eventually lowers the melting temperature of the mixture. In the process of firing, fluxes melt at an early stage. After which it forms a glassy matrix that bonds the other components of the system together. In the United States, roughly around 66% of feldspar are being consumed while in glassmaking, this includes glass containers and glass fiber as well. Ceramics (which are included in electrical insulators, sanitary ware, pottery, tableware, and tile) and other uses, like fillers.


A mnemonic device, also known as a memory device, is literally any learning technique that aids information retrieval in human memory.

Suppose facing a geography memorization task, a way to make the learning simple is by employing a mnemonic device. Mnemonics are the memory aids which are in the form of easily recalled rhymes, phrases, or even acronyms that serve as a reference for the place names (or other information) that one is trying to study.

One example – the common mnemonic device that helps people memorize the names of the Great Lakes. Suppose the word “HOMES,” the five lake names will fall into place and in mind, that is Huron, Ontario, Michigan, Erie, Superior.


Sunstone is a kind of plagioclase feldspar that is when viewed from certain directions exhibits an appearance of spangled beads. Sunstone is found in Sweden, Southern Norway, and other state localities. They are also found on some beaches and along the mid-coast of South Australia. 

For the reflections from the inclusions of red copper, we have an optical effect. They are in the form of minute scales, that are hexagonal, rhombic, or found in irregular shapes. They are disposed parallel to the cleavage-plan principle.  The inclusions give an effect to the stone of an appearance similar to aventurine. For this feature sunstone is also known as “aventurine-feldspar”. The optical effect is called schiller and Oregon being the color of the Sunstone is due to the presence of copper. The mid-section of this crystal sparkles, and usually this color is darkest in the middle and fades toward the outer edges.


Oligoclase is a mineral that is formed by a rock that belongs to the plagioclase feldspar.

Oligoclase is characterized by a high sodium feldspar crystallizing quality in the triclinic system. It is 6 to 6.5 as per the Mohs hardness and it has a specific gravity of 2.64 to 2.66. While, its refractive indices being nα=1.533–1.543, nβ=1.537–1.548, and nγ=1.542–1.552. In color texture, this is usually white in shade, with other shades of grey, red and green.

Oligoclase also occurs, often accompanying the orthoclase, which is a constituent of the plutonic igneous rocks like granite, syenite and diorite. This occurs in porphyry and in diabetic dikes and in sills as well. They are found in the volcanic rock andesite and in trachyte, where the presence is a defining feature. They also occur in gneiss. The developed and the most-largest crystals are the ones found with orthoclase, epidote, quartz, and calcite. The distinct texture of rapakivi granite is because of the oligoclase phenocrysts. Oligoclase is even found in the metamorphic rocks that are formed under transitional greenschist to amphibolite facies type conditions.  


Granulite Facies

Granulite facies are one of the major divisions of the mineral facies which are the types of metamorphic rocks, the rocks that are formed under the most intense temperature-pressure conditions are usually found in the regional metamorphism at the upper limit. At the uppermost limit of the facies, migmatite formation can occur. The temperature is 650–1,100 °C (1,200–2,000 °F) and a pressure of 3 to 10 kilobars (where 1 kilobar equals about 15,000 pounds per square inch) may be reached on. Under conditions of less intensified metamorphism, the rocks of the amphibolite facies occur. 

FAQ (Frequently Asked Questions)

1. Define Feldspar.

Ans. Feldspars which are KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8 are a group of forming rocks that are tectosilicate minerals that is about 41% of the Earth's continental crust measured by weight. Feldspars are in the crystallized form of magma as both the intrusive and extrusive igneous rocks are also present in quite many types of metamorphic rock.

Feldspar comes under the group of crystalline minerals consisting of aluminum silicates which are either potassium, calcium, sodium, or barium which are an essential constituents of nearly all types of crystalline rocks.

All the feldspars which are rock-forming minerals are of an aluminosilicate mineral with their general formula which is AT4O8 in which A = potassium, sodium, or calcium (Ca) T = silicon (Si) and aluminum (Al), with a-Si and Al ratio which ranges from 3:1 to 1:1.

2. What Type of Mineral is Feldspar?

Ans. Feldspar which is the name of a large group of rock-forming type minerals is silicate minerals that make up over 50% of the Earth's crust. They are found in these types of rocks - igneous, metamorphic, and sedimentary. Occurs in all parts of the world. The Feldspar minerals have structures, chemical compositions, and physical properties which are quite similar to each other.

Plagioclase feldspar is identified by its non-metallic property, they are vitreous to pearly luster; they are in white to dark gray color; they are two good cleavages at nearly 90o. Plagioclase feldspar has striations on some of their cleavage surfaces. Its hardness is 6 Mohs. They are of specific gravity. That is 2.6 to 2.8.

Feldspars are a hard type mineral, which has a hardness of 6 on the Mohs scale. They lie between the hardness of a steel knife (5.5) and the hardness of quartz which is 7. 

3. What Do You Mean by Aventurine?

Ans. Aventurine is a form of quartz, they are marked by the translucency and the presence of the platy mineral inclusions which give them a shimmering or a glistening effect which is termed as aventurescence.

Aventurine is a type of stone of prosperity. This reinforces the leadership qualities and decisiveness. The stone also promotes compassion and empathy. It encourages perseverance. Aventurine stone also relieves stammering tendency and severe neuroses.