Mylonites are a broad category of rock that may be made from many different mineral components. They are metamorphic and super fine-grained, and can take on a wide range of appearances. The rock is sometimes used as filler or in road construction.
Density:
2.65 - 2.85 g/cm³
On This Page
Properties
Values
Characteristics
Cultural
Common Questions
General Info About Mylonite
Instantly Identify Rocks with a Snap
Snap a photo for instant rock/gemstone/mineral ID and properties analysis, gaining quick insights on characteristics, market value, collecting tips, care, real vs fake, and health risks, etc.
Download the App for Free
Physical Properties of Mylonite
Texture
Foliated
Colors
Variable, often grey to black
Magnetism
Potentially Magnetic
Grain Size
Fine grained
Density
2.65 - 2.85 g/cm³, Normal Weight
AI rock expert in your pocket
Discover the Value of Mylonite
Discovering the Diverse Values of Rocks
Unveiling the Rarity, Aesthetics, and Economic Significance of Rocks
Download the App for Free
Rarity
Uncommon
Characteristics of Mylonite
Your Comprehensive Rock Characteristics Guide
In-depth exploration of rock types, features, and formation aspects
Download the App for Free
Rock Types of Mylonite
Blastomylonites are coarse grained, often sugary in appearance without distinct tectonic banding.
Ultramylonites usually have undergone extreme grainsize reduction. In structural geology, ultramylonite is a kind of mylonite defined by modal percentage of matrix grains more than 90%. Ultramylonite is often hard, dark, cherty to flinty in appearance and sometimes resemble pseudotachylite and obsidian. In reverse, ultramylonite-like rocks are sometimes "deformed pseudotachylyte".
Mesomylonites have undergone an appreciable amount of grainsize reduction, and are defined by their modal percentage of matrix grains being between 50 and 90%.
Protomylonites are mylonites which have experienced limited grainsize reduction, and are defined by their modal percentage of matrix grains being less than 50%. Because mylonitisation is incomplete in these rocks, relict grains and textures are apparent, and some protomylonites can resemble foliated cataclasite or even some schists.
Phyllonites are phyllosilicate(e.g. chlorite or mica)-rich mylonites. They typically have a well-developed secondary shear (C') fabric.
Formation of Mylonite
Mylonite are ductilely deformed rocks formed by the accumulation of large shear strain, in ductile fault zones. There are many different views on the formation of mylonites, but it is generally agreed that crystal-plastic deformation must have occurred, and that fracturing and cataclastic flow are secondary processes in the formation of mylonites. Mechanical abrasion of grains by milling does not occur, although this was originally thought to be the process that formed mylonites, which were named from the Greek μύλος mylos, meaning mill. Mylonite form at depths of no less than 4 km.
Cultural Significance of Mylonite
Your Ultimate Guide to Understanding Rock Culture
Unveiling the mysteries of rock culture - exploring uses, history, and healing properties, etc
Download the App for Free
Uses of Mylonite
Like many other strong and durable rocks, mylonite is often only associated with construction materials. When cut in large blocks, mylonite is particularly good in building foundations, paving, and walling. It is commonly used in gardens for decorative purposes, and may be crushed to be used as road aggregate.
Common Questions People Also Ask
Get Quick Rock Answers with a Snap
Snap a photo for instant rock ID and answers on characteristics, market value, collecting tips, care, real vs fake, and health risks, etc.
