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
Marl is an unconsolidated sedimentary rock consisting of clay and lime
Discoverer
Unknown
William Smith
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From Old French marle, from Late Latin marglia
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Banded, Foliated, Platy
Earthy
Color
Black, Brown, Pink, Red, White
Beige, Brown, Green, Grey, White
Durability
Durable
Durable
Appearance
Foliated
Rough and Dull
Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Decorative Aggregates, Floor Tiles
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, Roof Tiles
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Antiquity Uses
Artifacts
Artifacts, Jewellery, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
Creating Artwork, Soil Conditioner
Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Clay Marl ,Blue Marl, Red Marl, High Bank Marl, Shell Layer Marl, Under Shell Layer Marl, Sand Marl, Green Marl, Grey Marl and Clayey Marl
Features
Generally rough to touch, Is one of the oldest rock
Generally rough to touch, Is one of the oldest rock, Splintery, Very fine grained rock
Archaeological Significance
Famous Monuments
Konark Sun Temple in India, Washington Monument, US
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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.
Marl forms when very fine-grained clay particles are deposited in water which settles at the bottom of water bodies and are compacted by overlying sediment; the water squeezes out and hence forming Marl rock.
Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Calcite, Clay, Dolomite, Gypsum, Micas, Pyrite, Quartz
Compound Content
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, Silicon Dioxide
Types of Metamorphism
Impact Metamorphism
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Types of Weathering
Biological Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion
Grain Size
Medium to Coarse Grained
Very fine-grained
Fracture
Irregular
Conchoidal
Porosity
Very Less Porous
Highly Porous
Specific Gravity
2.5-2.7
2.2-2.8
Transparency
Translucent to Opaque
Opaque
Density
2.6-2.9 g/cm3
2.4-2.8 g/cm3
Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
India, Pakistan, Russia
Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
Ethiopia, Kenya, Morocco, South Africa
Europe
Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Deposits in Western Continents
North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
USA
South America
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria
New South Wales, Victoria, Western Australia