Definition
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
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
Origin
Romania and Moldova, Europe
Unknown
Discoverer
Unknown
Unknown
Etymology
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described
From Latin Argilla (clay) and -ite in English which became agrilla+ -ite = Argillite
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Soft Rock
Group
Volcanic
Not Applicable
Other Categories
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic to Porphyritic
Clastic, Polished
Color
Bluish - Grey, Brown, Grey, Light to Dark Grey
Dark Grey to Black, Pink, Red, White
Durability
Durable
Durable
Appearance
Vesicular
Rough and Dull
Interior Uses
Decorative Aggregates, Entryways, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, Paving Stone, Garden Decoration
As Building Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing, Whetstones
Construction Industry
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Used for flooring, stair treads, borders and window sills.
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture
Commercial Uses
Commemorative Tablets, Creating Artwork
Fire resistant, Used to manufracture paperweights and bookends
Types
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Not Available
Features
Host Rock for Lead, Is one of the oldest rock
Is one of the oldest rock
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Figurines
Not Yet Used
Used
Formation
Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.
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
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Compound Content
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Iron(III) Oxide, Potassium Oxide, MgO, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism
Not Applicable
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering
Types of Erosion
Chemical Erosion
Chemical Erosion
Grain Size
Medium to Fine Coarse Grained
Fine Grained
Fracture
Conchoidal
Conchoidal to Uneven
Streak
White
White to Grey
Porosity
Less Porous
Highly Porous
Luster
Subvitreous to Dull
Waxy and Dull
Toughness
Not Available
2.6
Specific Gravity
2.86-2.87
2.56-2.68
Transparency
Translucent
Opaque
Density
2.77-2.771 g/cm3
2.54-2.66 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
Not Yet Found
Bangladesh, China, India, Russia
Africa
Not Yet Found
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Europe
France, Greece, Romania, Scotland, Spain
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand, South Australia, Western Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia