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
Amphibolite can be defined as a granular metamorphic rock which mainly consist of hornblende and plagioclase
Discoverer
Unknown
Alexandre Brongniart
Etymology
From Latin Argilla (clay) and -ite in English which became agrilla+ -ite = Argillite
From Amphibole + -ite
Class
Sedimentary Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Clastic, Polished
Banded, Foliated, Massive
Color
Dark Grey to Black, Pink, Red, White
Black, Brown, Green, Grey
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Rough and Dull
Foliated
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Countertops, Decorative Aggregates, Entryways, Floor Tiles, Flooring, Homes, Hotels, Kitchens
Exterior Uses
As Building Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Office Buildings
Other Architectural Uses
Curbing, Whetstones
Curbing
Construction Industry
Used for flooring, stair treads, borders and window sills.
As Dimension Stone, Building houses or walls, Cobblestones, Construction Aggregate, for Road Aggregate, Landscaping, Production of Glass and Ceramics, Roadstone
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts, Sculpture, Small Figurines
Commercial Uses
Fire resistant, Used to manufracture paperweights and bookends
Cemetery Markers, Commemorative Tablets, Creating Artwork
Types
Metamorphic rock
Hornblendite
Features
Is one of the oldest rock
Clasts are smooth to touch, Matrix variable, Surfaces are often shiny
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.
Amphibolite is a coarse-grained metamorphic rock which forms by metamorphism of mafic igneous rocks like basalt and gabbro or from the metamorphism of clay-rich sedimentary rocks like marl or graywacke.
Mineral Content
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Amphibole, Andalusite, Biotite, Calcite, Epidote, Garnet, Hornblade, Kyanite, Magnetite, Olivine, Plagioclase, Pyroxene, Staurolite, Wollastonite
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
-
-
Types of Weathering
Biological Weathering
Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Wind Erosion
Grain Size
Fine Grained
Medium to Coarse Grained
Fracture
Conchoidal to Uneven
Irregular to Conchoidal
Streak
White to Grey
White to Grey
Porosity
Highly Porous
Less Porous
Luster
Waxy and Dull
Vitreous to Dull
Specific Gravity
2.56-2.68
2.5
Transparency
Opaque
Opaque
Density
2.54-2.66 g/cm3
2.85-3.07 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Bangladesh, China, India, Russia
Russia, Turkey
Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Madagascar, Rwanda, Somalia, South Africa, Sudan, Tanzania, Uganda
Europe
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Germany, Greece, Iceland, Norway, Poland
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
South Australia, Western Australia