Definition
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
Epidosite is a highly altered epidote and quartz bearing rock which is a type of metasomatite, essentially altered basalt
Discoverer
Unknown
Unknown
Etymology
From Latin Argilla (clay) and -ite in English which became agrilla+ -ite = Argillite
-
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Medium Hardness Rock
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Opaque Rock
Texture
Clastic, Polished
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Color
Dark Grey to Black, Pink, Red, White
Black, Brown, Light to Dark Grey
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Rough and Dull
Dull and Soft
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Floor Tiles, Homes, Hotels, Interior Decoration
Exterior Uses
As Building Stone, Garden Decoration, Office Buildings
As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Curbing, Whetstones
Curbing
Construction Industry
Used for flooring, stair treads, borders and window sills.
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Fire resistant, Used to manufracture paperweights and bookends
Commemorative Tablets, Creating Artwork
Types
Metamorphic rock
Alkaline Basalt, Boninite, High Alumina Basalt, Mid Ocean Ridge Basalt (MORB), Tholeiitic Basalt, Basaltic trachyandesite, Mugearite and Shoshonite
Features
Is one of the oldest rock
Has High structural resistance against erosion and climate, Very fine grained rock
Archaeological Significance
Formation
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.
Epidosite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
Mineral Content
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Olivine, Plagioclase, Pyroxene
Compound Content
Iron(III) Oxide, Potassium Oxide, MgO, Silicon Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism
Types of Weathering
Biological Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion
-
Grain Size
Fine Grained
Fine to Coarse Grained
Fracture
Conchoidal to Uneven
Conchoidal
Streak
White to Grey
White to Grey
Porosity
Highly Porous
Less Porous
Specific Gravity
2.56-2.68
2.8-3
Transparency
Opaque
Opaque
Density
2.54-2.66 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Bangladesh, China, India, Russia
India, Russia
Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
South Africa
Europe
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Iceland
Deposits in Western Continents
North America
USA
Canada, USA
South America
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Brazil
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia
-