Definition
Shonkinite is a rare, dark-coloured and intrusive igneous rock which contains augite and orthoclase feldspar as its primary constituents
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
Origin
USA
Romania and Moldova, Europe
Discoverer
Unknown
Unknown
Etymology
From the name of Shonkin Sag ranges in the Highwood Mountains of north-central Montana, US
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Earthy
Aphanitic to Porphyritic
Color
Brown, Buff, Cream, Green, Grey, Pink, White
Bluish - Grey, Brown, Grey, Light to Dark Grey
Durability
Durable
Durable
Appearance
Banded and Foilated
Vesicular
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, Paving Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate, Landscaping, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Antiquity Uses
Artifacts, Monuments, Sculpture
Artifacts
Commercial Uses
Cemetery Markers, Creating Artwork
Commemorative Tablets, Creating Artwork
Types
Igneous rock
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Features
Available in Lots of Colors and Patterns, Is one of the oldest rock, Matrix variable
Host Rock for Lead, Is one of the oldest rock
Archaeological Significance
Formation
Shonkinites are formed due to alkaline igneous activities and are generally formed in thick continental crustal areas or in Cordilleran subduction zones.
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.
Mineral Content
Amphibole, Biotite, Feldspar, Hornblade, Micas, Muscovite or Illite, Plagioclase, Pyroxene, Quartz
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion, Water Erosion
Chemical Erosion
Grain Size
Medium to Fine Coarse Grained
Medium to Fine Coarse Grained
Porosity
Less Porous
Less Porous
Luster
Subvitreous to Dull
Subvitreous to Dull
Specific Gravity
2.6-2.7
2.86-2.87
Transparency
Opaque
Translucent
Density
2.6-2.8 g/cm3
2.77-2.771 g/cm3
Resistance
Heat Resistant, Impact Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
-
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
-
Europe
Bulgaria, England, Germany, Norway, Romania, Switzerland
France, Greece, Romania, Scotland, Spain
Deposits in Western Continents
South America
Brazil, Chile
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand, Queensland, South Australia, Western Australia
New Zealand, South Australia, Western Australia