Definition
Very fine grained fault rock which is composed of glassy matrix that often contains inclusions of wall-rock fragments.
Argillites are highly compact sedimentary or slightly metamorphosed rocks that consist largely or wholly of particles of clay or silt but lack the fissility of shale or the cleavage characteristic of slate
Discoverer
Unknown
Unknown
Etymology
From pseudo- + tachylite, a glassy rock generated by frictional heat within faults.
From Latin Argilla (clay) and -ite in English which became agrilla+ -ite = Argillite
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Quench
Clastic, Polished
Color
Black, Brown, Green, Grey, Pink, White
Dark Grey to Black, Pink, Red, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull and Soft
Rough and Dull
Interior Uses
Decorative Aggregates, Entryways, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration
As Building Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing, Whetstones
Construction Industry
As Dimension Stone, Cement Manufacture, for Road Aggregate, Making natural cement
Used for flooring, stair treads, borders and window sills.
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture
Commercial Uses
Creating Artwork, Gemstone
Fire resistant, Used to manufracture paperweights and bookends
Types
Cataclastic rock
Metamorphic rock
Features
Host Rock for Lead
Is one of the oldest rock
Archaeological Significance
Formation
Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Pseudotachylite is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.
An argillite is a fine-grained sedimentary rock mainly composed of clay particles which forms from lithified muds which contain variable amounts of silt-sized particles.
Mineral Content
Iron Oxides, Pyroxene, Quartz, Stishovite, Sulfides
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Compound Content
Carbon Dioxide, Silicon Dioxide, Sulfur Dioxide, Sulphur
Iron(III) Oxide, Potassium Oxide, MgO, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
-
Types of Weathering
-
Biological Weathering
Types of Erosion
-
Chemical Erosion
Grain Size
Very fine-grained
Fine Grained
Fracture
Uneven
Conchoidal to Uneven
Streak
Light to dark brown
White to Grey
Porosity
Less Porous
Highly Porous
Luster
Vitreous
Waxy and Dull
Specific Gravity
2.46-2.86
2.56-2.68
Transparency
Transparent to Translucent
Opaque
Density
2.7-2.9 g/cm3
2.54-2.66 g/cm3
Resistance
Heat Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
South Korea
Bangladesh, China, India, Russia
Africa
Western Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Europe
Great Britain, Switzerland
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Deposits in Western Continents
South America
-
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
Central Australia, Western Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia
All about Pseudotachylite and Argillite Properties
Know all about Pseudotachylite and Argillite properties here. All properties of rocks are important as they define the type of rock and its application. Pseudotachylite belongs to Metamorphic Rocks while Argillite belongs to Sedimentary Rocks.Texture of Pseudotachylite is Quench whereas that of Argillite is Clastic, Polished. Pseudotachylite appears Dull and Soft and Argillite appears Rough and Dull. The luster of Pseudotachylite is vitreous while that of Argillite is waxy and dull. Pseudotachylite is available in black, brown, green, grey, pink, white colors whereas Argillite is available in dark grey to black, pink, red, white colors. The commercial uses of Pseudotachylite are creating artwork, gemstone and that of Argillite are fire resistant, used to manufracture paperweights and bookends.