Shale and Porphyry
Definition
Definition
Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
History
Origin
Unknown
Egypt
Discoverer
Unknown
Unknown
Etymology
From German Schalstein laminated limestone, and Schalgebirge layer of stone in stratified rock. From Old English scealu in its base sense of- thing that divides or separate,
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Family
Group
Not Applicable
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Texture
Clastic, Splintery
Porphyritic
Color
Black, Brown, Buff, Green, Grey, Red, Yellow
Black, Brown, Colourless, Green, Grey, Red, Rust, White
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
No
No
Scratch Resistant
No
Yes
Stain Resistant
No
Yes
Wind Resistant
No
No
Acid Resistant
No
Yes
Appearance
Muddy
Dull
Uses
Architecture
Interior Uses
Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Office Buildings
Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Construction Aggregate
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Sculpture
Artifacts, Monuments, Sculpture
Other Uses
Commercial Uses
Creating Artwork, Pottery
Creating Artwork, Gemstone, Jewelry
Types
Types
Red Shale, Black Shale, Green Shale, Grey Shale and Yellow Shale
Rhomb Porphyry
Features
Easily splits into thin plates, Generally rough to touch, Very fine grained rock
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Archaeological Significance
Monuments
Used
Used
Famous Monuments
Jantar Mantar in India
Data Not Available
Sculpture
Used
Used
Famous Sculptures
Data Not Available
Data Not Available
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Used
Used
Fossils
Present
Absent
Formation
Formation
Shale forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are later compacted hence forming shale.
Porphyry is formed in two stages: the magma cools slowly deep within the crust or the magma is cools rapidly as it erupts from a volcano, creating small grains that are usually invisible to naked eye.
Composition
Mineral Content
Albite, Biotite, Calcite, Chert, Chlorite, Dolomite, Hematite, Micas, Muscovite or Illite, Pyrite, Quartz, Silica, Sulfides
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Compound Content
Ca, Fe, Mg, Silicon Dioxide, Sodium
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Transformation
Metamorphism
No
Yes
Types of Metamorphism
Not Applicable
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Not Registered
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Properties
Physical Properties
Hardness
3
6-7
Grain Size
Very fine-grained
Fine Grained
Fracture
Not Available
Irregular
Streak
White
White
Porosity
Highly Porous
Less Porous
Luster
Dull
Dull
Compressive Strength
95.00 N/mm2
20
Not Available
Cleavage
Slaty
Imperfect
Toughness
2.6
1.7
Specific Gravity
2.2-2.8
2.5-4
Transparency
Opaque
Translucent to Opaque
Density
2.4-2.8 g/cm3
2.5-2.52 g/cm3
Thermal Properties
Specific Heat Capacity
0.39 kJ/Kg K
23
Not Available
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant
Reserves
Deposits in Eastern Continents
Asia
Bangladesh, China, India, Russia
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Egypt, Ethiopia, Ghana, South Africa
Europe
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Others
Not Yet Found
Greenland
Deposits in Western Continents
North America
USA
Canada, Cuba, Jamaica, USA
South America
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia
New South Wales, New Zealand, Western Australia
All about Shale and Porphyry Properties
Know all about Shale and Porphyry properties here. All properties of rocks are important as they define the type of rock and its application. Shale belongs to Sedimentary Rocks while Porphyry belongs to Igneous Rocks.Texture of Shale is Clastic, Splintery whereas that of Porphyry is Porphyritic. Shale appears Muddy and Porphyry appears Dull. The luster of Shale and Porphyry is dull. Shale is available in black, brown, buff, green, grey, red, yellow colors whereas Porphyry is available in black, brown, colourless, green, grey, red, rust, white colors. The commercial uses of Shale are creating artwork, pottery and that of Porphyry are creating artwork, gemstone, jewelry.
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