Definition
Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock
Shale is a fine-grained sedimentary rock which is formed by the compaction of silt and clay-size mineral particles
History
Origin
Germany
-
Discoverer
Van Tooren
Johann Gottlob Lehmann
Etymology
From Greek tephra, ashes from Indo-European base, to burn
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,
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
-
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic to Porphyritic
Clastic, Splintery
Color
Black, Brown, Green, Grey, White
Black, Brown, Buff, Green, Grey, Red, Yellow
Maintenance
Less
More
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Vesicular
Muddy
Architecture
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Office Buildings
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Landscaping
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Medical Industry
-
-
Antiquity Uses
Artifacts, Sculpture
Artifacts, Sculpture
Other Uses
Commercial Uses
Production of Lime, Soil Conditioner
Creating Artwork, Pottery
Types
Igneous rock
Red Shale, Black Shale, Green Shale, Grey Shale and Yellow Shale
Features
Host Rock for Lead
Easily splits into thin plates, Generally rough to touch, Very fine grained rock
Archaeological Significance
Monuments
-
-
Famous Monuments
-
Jantar Mantar in India
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Present
Formation
Tephrite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.
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.
Composition
Mineral Content
Alkali feldspar, Nepheline, Plagioclase, Pyroxene
Albite, Biotite, Calcite, Chert, Chlorite, Dolomite, Hematite, Micas, Muscovite or Illite, Pyrite, Quartz, Silica, Sulfides
Compound Content
CaO, Carbon Dioxide, MgO, Silicon Dioxide
Ca, Fe, Mg, Silicon Dioxide, Sodium
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
-
Weathering
✔
✘
✔
✘
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
✔
✘
✔
✘
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Physical Properties
Hardness
6.53
1
7
👆🏻
Grain Size
Medium to Fine Coarse Grained
Very fine-grained
Fracture
Uneven
-
Streak
Bluish Black
White
Porosity
Very Less Porous
Highly Porous
Luster
Subvitreous to Dull
Dull
Compressive Strength
90.00 N/mm295.00 N/mm2
0.15
450
👆🏻
Cleavage
Crenulation and Pervasive
Slaty
Toughness
2.4
2.6
Specific Gravity
2.862.2-2.8
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
2.8-2.9 g/cm32.4-2.8 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.92 kJ/Kg K0.39 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
-
Bangladesh, China, India, Russia
Africa
Namibia, Uganda
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Europe
Germany, Hungary, Italy, Portugal, Spain
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Others
-
-
Deposits in Western Continents
North America
USA
USA
South America
-
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand, Western Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia