Gneiss and Scoria
Definition
Definition
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks
Scoria is a dark-colored extrusive igneous rock with abundant round bubble-like cavities
History
Discoverer
Unknown
Unknown
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From late Middle English (denoting slag from molten metal), from Greek skōria refuse, from skōr dung
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Not Applicable
Volcanic
Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Banded, Foliated, Platy
Vesicular
Color
Black, Brown, Pink, Red, White
Black, Brown, Dark Grey to Black, Red
Maintenance
More
More
Durability
Durable
Durable
Water Resistant
Yes
Yes
Scratch Resistant
Yes
Yes
Stain Resistant
Yes
No
Wind Resistant
Yes
No
Acid Resistant
No
No
Appearance
Foliated
Glassy and Vesicular
Uses
Architecture
Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
As Dimension Stone
Cement Manufacture, Construction Aggregate, for Road Aggregate, In landscaping and drainage works
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture
Other Uses
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
As a traction material on snow-covered roads, Creating Artwork, High-temperature insulation, In gas barbecue grills
Types
Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Not Available
Features
Generally rough to touch, Is one of the oldest rock
Available in Lots of Colors and Patterns, Generally rough to touch, Surfaces are often shiny
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Konark Sun Temple in India, Washington Monument, US
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Pictographs
Not Used
Used
Petroglyphs
Not Used
Used
Figurines
Not Yet Used
Used
Fossils
Absent
Absent
Formation
Formation
Gneiss is a high grade metamorphic rock i.e. it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of Gneiss forms from volcanic rock, shale or granitie.
Scoria forms when magma containing huge amount of dissolved gas flows from a volcano during an eruption.
Composition
Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Apatite, Biotite, Calcite, Feldspar, Hematite, Hornblade, Ilmenite, Magnetite, Olivine, Pyroxene, Quartz, Silica
Compound Content
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Ca, NaCl
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Impact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Properties
Physical Properties
Hardness
7
5-6
Grain Size
Medium to Coarse Grained
Fine Grained
Fracture
Irregular
Conchoidal
Streak
White
White
Porosity
Very Less Porous
Highly Porous
Luster
Dull
Subvitreous to Dull
Compressive Strength
125.00 N/mm2
17
Not Available
Cleavage
Poor
Perfect
Toughness
1.2
2.1
Specific Gravity
2.5-2.7
Not Available
Transparency
Translucent to Opaque
Opaque
Density
2.6-2.9 g/cm3
Not Available
Thermal Properties
Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
Afghanistan, Indonesia, Japan, Russia
Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Ethiopia, Kenya, Tanzania
Europe
Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom
Greece, Hungary, Iceland, Italy, Turkey
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
Bahamas, Barbados, Canada, Costa Rica, Cuba, Jamaica, Mexico, USA
South America
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
Argentina, Chile, Ecuador, Peru
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria
New Zealand, Western Australia
All about Gneiss and Scoria Properties
Know all about Gneiss and Scoria properties here. All properties of rocks are important as they define the type of rock and its application. Gneiss belongs to Metamorphic Rocks while Scoria belongs to Igneous Rocks.Texture of Gneiss is Banded, Foliated, Platy whereas that of Scoria is Vesicular. Gneiss appears Foliated and Scoria appears Glassy and Vesicular. The luster of Gneiss is dull while that of Scoria is subvitreous to dull. Gneiss is available in black, brown, pink, red, white colors whereas Scoria is available in black, brown, dark grey to black, red colors. The commercial uses of Gneiss are cemetery markers, jewelry, tombstones, used in aquariums and that of Scoria are as a traction material on snow-covered roads, creating artwork, high-temperature insulation, in gas barbecue grills.
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