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How does the cleavage of graphite differ from mica?
Types of cleavage Basal or pinacoidal cleavage occurs when there is only one cleavage plane. Graphite has basal cleavage. Mica (like muscovite or biotite) also has basal cleavage; this is why mica can be peeled into thin sheets. Cubic cleavage occurs when there are three cleavage planes intersecting at 90 degrees.
What is the cleavage of minerals and how does mica cleave?
Scientific discussion: Cleavage is related to the underlying structure of the mineral. In the case of mica, the mineral consists of planar sheets of atoms with relatively weak bonds between the sheets. This enables us to easily split micas into very thin sheets. We call this perfect basal cleavage.
How does cleavage differ from a fracture?
Cleavage is the property of a mineral that allows it to break smoothly along specific internal planes (called cleavage planes) when the mineral is struck sharply with a hammer. Fracture is the property of a mineral breaking in a more or less random pattern with no smooth planar surfaces.
How does mica break?
Mica is a good example – breaking along very closely spaced flat planes that yield thin “sheets.” Calcite is another good example, breaking along three different planes that yield blocky fragments that look like a rectangular box that has been warped – called a “rhombohedron” or, simply, “rhomb.” Galena breaks along …
Why is graphite so strong?
Contrary to common belief, the chemical bonds in graphite are actually stronger than those that make up diamond. While within each layer of graphite the carbon atoms contain very strong bonds, the layers are able to slide across each other, making graphite a softer, more malleable material.
Why does Mica always break flat sheets?
It breaks along flat surfaces because the bonds between its atoms are less strong in some directions than in others.
Why is mica bad?
The main risk associated with mica is inhalation. Mica can be dangerous if it is inhaled because the particles can get into the lungs and cause scarring. Thus, any powder or aerosol products containing mica are the most concerning.
Is mica rock worth anything?
Sheet mica prices vary with grade and can range from less than $1 per kilogram for low-quality mica to more than $2,000 per kilogram for the highest quality.
What are the similarities and differences between fracture and cleavage?
Cleavage is the way a break happens along a weak plane of the mineral, and fracture is the way a break happens along a strong plane of the mineral. Fractures never result in two like pieces, rather, all at different sizes, shapes, and angles.