Definition
Eclogite is an extreme metamorphic rock, formed by regional metamorphism of basalt rock under very high pressure and temperature
  
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
  
History
  
  
Origin
Unknown
  
Iceland
  
Discoverer
René Just Haüy
  
Unknown
  
Etymology
From French, Greek eklogē selection with reference to the selective content of the rock + -ite1
  
From German Tachylite, from tachy- + Greek lutos soluble, melting
  
Class
Metamorphic Rocks
  
Igneous Rocks
  
Sub-Class
Durable Rock, Medium Hardness Rock
  
Durable Rock, Medium Hardness Rock
  
Family
  
  
Group
Not Applicable
  
Volcanic
  
Other Categories
Fine Grained Rock, Opaque Rock
  
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
  
Texture
Earthy
  
Vitreous
  
Color
Black, Brown, Colourless, Green, Grey, Pink, White
  
Black, Dark Brown
  
Maintenance
Less
  
More
  
Durability
Durable
  
Durable
  
Water Resistant
No
  
Yes
  
Scratch Resistant
Yes
  
No
  
Stain Resistant
Yes
  
No
  
Wind Resistant
Yes
  
Yes
  
Acid Resistant
No
  
Yes
  
Appearance
Dull, Banded and Foilated
  
Glassy
  
Architecture
  
  
Interior Uses
Decorative Aggregates, Interior Decoration
  
Decorative Aggregates, Interior Decoration
  
Exterior Uses
Paving Stone, Garden Decoration
  
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
  
Other Architectural Uses
Curbing
  
Curbing
  
Industry
  
  
Construction Industry
Not Yet Used
  
Cutting Tool, Knives, Landscaping, Scrapers
  
Medical Industry
In Chemical and Pharmaceutical Industry, Medicines and Cosmetics
  
Not Yet Used
  
Antiquity Uses
Artifacts
  
Artifacts
  
Other Uses
  
  
Commercial Uses
Creating Artwork, Gemstone
  
Cemetery Markers, Creating Artwork
  
Types
Not Available
  
Not Available
  
Features
Available in Lots of Colors and Patterns, Generally rough to touch, Is one of the oldest rock
  
Available in Lots of Colors and Patterns, Clasts are smooth to touch, NA
  
Archaeological Significance
  
  
Monuments
Not Yet Used
  
Not Yet Used
  
Famous Monuments
Not Applicable
  
Not Applicable
  
Sculpture
Not Yet Used
  
Not Yet Used
  
Famous Sculptures
Not Applicable
  
Not Applicable
  
Pictographs
Used
  
Used
  
Petroglyphs
Used
  
Used
  
Figurines
Not Yet Used
  
Not Yet Used
  
Fossils
Absent
  
Absent
  
Formation
Eclogite forms from high-pressure metamorphism of mafic igneous rocks mainly, basalt or gabbro as it plunges into the mantle in a subduction zone.
  
Tachylite 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.
  
Composition
  
  
Mineral Content
Amphibole, Coesite, Corundum, Dolomite, Garnet, Kyanite, Lawsonite, Paragonite, Phengite, Pyroxene, Quartz, Rutile, Zoisite
  
Feldspar, Olivine
  
Compound Content
Aluminium Oxide, NaCl, CaO, Carbon Dioxide, Iron(III) Oxide, Magnesium Carbonate, MgO, Sodium Oxide, Potassium, Sodium
  
Fe, Mg
  
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
Mechanical Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Sea Erosion
  
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
3.5-4
  
5.5
  
Grain Size
Fine Grained
  
Medium to Fine Coarse Grained
  
Fracture
Not Available
  
Conchoidal
  
Streak
White
  
Vermilion
  
Porosity
Less Porous
  
Less Porous
  
Luster
Subvitreous to Dull
  
Resinous
  
Compressive Strength
Not Available
  
206.00 N/mm
2
  
8
Cleavage
Perfect
  
Not Available
  
Toughness
Not Available
  
Not Available
  
Specific Gravity
2.86-2.87
  
2.4
  
Transparency
Opaque
  
Opaque
  
Density
3.2-3.6 g/cm3
  
3.058 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
Not Available
  
0.56 kJ/Kg K
  
22
Resistance
Heat Resistant
  
Heat Resistant, Impact Resistant, Wear Resistant
  
Deposits in Eastern Continents
  
  
Asia
India, Kazakhstan, Kuwait, Russia, South Korea, Thailand, Turkey
  
Cambodia, Russia, South Korea
  
Africa
Ethiopia, Morocco, South Africa
  
East Africa
  
Europe
France, Germany, Italy, Norway, Scotland
  
England, Germany, Hungary, Iceland, Scotland, Sweden
  
Others
Greenland
  
Hawaii Islands
  
Deposits in Western Continents
  
  
North America
Canada, Costa Rica, Panama, USA
  
USA
  
South America
Argentina, Brazil, Colombia, Ecuador
  
Not Yet Found
  
Deposits in Oceania Continent
  
  
Australia
Central Australia, New Zealand, Queensland
  
Victoria