The compilation of these Minerals and Energy Resources Notes makes students exam preparation simpler and organised.
Agate
Introduction to Agate
Agate refers to a semiprecious silica mineral. It occurs in a variety of minerals and has a transparent nature. This mineral comes in a huge range of colours like brown, white, grey, red, yellow, and black.
These colours are the result of impurities which take place due to alternating bands within the agate. Students can explore more about this mineral and its various types and uses here.
Agate Meaning and Definition
Agate refers to a rock that consists primarily of cryptocrystalline silica which is primarily chalcedony. Its main characteristic is the fineness of grain and variety of colour.
Agates are available in a variety of host rocks. However, they are mostly available in volcanic rocks.
This mineral is certainly a unique variety of micro-crystalline quartz of translucent nature. When agates are of high quality and impressive, they are treated as precious stones. The formation of agates is due to the deposition of silica from groundwater in igneous rocks cavities.
Types of Agates
Following the various types of agates which are available:
Moss agate: These refer to semi-precious gemstones whose formation takes place from silicon dioxide. Furthermore, moss agate is a form of chalcedony that includes minerals of a green colour that are embedded in the stone.
Mexican agate: These agates show only a single eye. Furthermore, their other name is Cyclops agates. Moreover, they include a matter of green, red, golden, black, or other colours.
Also, they include a combination of colours which are embedded in the chalcedony and the disposition is in filaments and other forms which are suggestive of vegetable growth.
Dendritic agate: These include fern-like patterns whose formation takes place as a result of the presence of manganese and iron oxides.
Turritella agate- These agates are formed from silicified fossils. Furthermore, these silicified fossils are Elimia tenera (erroneously considered Turritella) shells.
Coldwater agate: The formation of such agates was not due to volcanic processes, but rather it was within the limestone and dolomite strata of marine origin. Furthermore, their formation results from silica gels.
Moreover, such agates are less colourful in nature. Above all, they have lines of white and grey chalcedony.
Brazilian agate: These agates come in sizable geodes of layered nodules. These agates occur in brownish tones with layers of white and grey. Moreover, these agates are moistly dyed in a variety of colours for ornamental purposes.
Lace agate: Lace agates are a unique variety that exhibits a lace-like pattern. Above all, their major forms include eyes, swirls, bands, or zigzags.
Uses of Agate
Major industrial uses of agates involve exploiting its hardness, ability to retain a surface finish of the high polish. Furthermore, other uses include tough resistance to chemical attacks. The traditional usage of agates has been in making knife-edge bearings for laboratory balances and precision accurate pendulum.
Individuals sometimes use agates to make mortars and pestles to crush and mix chemicals. Another important usage of agates is for leather burnishing tools.
Agates are useful for various types of decorative displays. Moreover, many experts use them for cabochons, beads, carvings, and Intarsia art also.
Example:
Question:
Which of the following is not a type of agates?
A. Desert agates
B. Greek agates
C. Brazilian agates
D. Coldwater agates
Answer:
The correct option is option “A” which is desert agates. This is because there is no such thing as desert agates. The other three options are certainly of agates.