Definition
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
Schist is a medium grade metamorphic rock with medium to large, flat, sheet like grains in a preferred orientation
History
Origin
Iceland
-
Discoverer
Unknown
Unknown
Etymology
From German Tachylite, from tachy- + Greek lutos soluble, melting
From French schiste, Greek skhistos i.e. split
Class
Igneous Rocks
Metamorphic Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Family
Group
Volcanic
-
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Vitreous
Foliated, Platy
Color
Black, Dark Brown
Black, Blue, Brown, Dark Brown, Green, Grey, Silver
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
✔
✘
✔
✘
Scratch Resistant
✔
✘
✔
✘
Stain Resistant
✔
✘
✔
✘
Wind Resistant
✔
✘
✔
✘
Acid Resistant
✔
✘
✔
✘
Appearance
Glassy
Layered and Shiny
Architecture
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Floor Tiles, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
-
Industry
Construction Industry
Cutting Tool, Knives, Landscaping, Scrapers
As Dimension Stone, Building houses or walls, Cement Manufacture, for Road Aggregate, Roadstone
Medical Industry
-
-
Antiquity Uses
Artifacts
Artifacts
Other Uses
Commercial Uses
Cemetery Markers, Creating Artwork
Used in aquariums, Writing Slates
Types
Volcanic glass
Mica Schists, Calc-Silicate Schists, Graphite Schists, Blueschists, Whiteschists, Greenschists, Hornblende Schist, Talc Schist, Chlorite Schist, Garnet Schist, Glaucophane schist.
Features
Available in Lots of Colors and Patterns, Clasts are smooth to touch
Easily splits into thin plates, Smooth to touch
Archaeological Significance
Monuments
-
-
Famous Monuments
-
-
Sculpture
-
-
Famous Sculptures
-
-
Pictographs
-
-
Petroglyphs
-
-
Figurines
-
-
Fossils
Absent
Absent
Formation
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.
Schist formed by dynamic metamorphism at high temperatures and pressures that aligns the grains of mica, hornblende and other elongated minerals into thin layers.
Composition
Mineral Content
Feldspar, Olivine
Alusite, Amphibole, Biotite, Chlorite, Epidote, Feldspar, Garnet, Graphite, Hornblade, Kyanite, Micas, Muscovite or Illite, Porphyroblasts, Quartz, Sillimanite, Staurolite, Talc
Compound Content
Fe, Mg
CaO, Carbon Dioxide, MgO
Transformation
Metamorphism
✔
✘
✔
✘
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal 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, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Physical Properties
Hardness
5.53.5-4
1
7
👆🏻
Grain Size
Medium to Fine Coarse Grained
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Streak
Vermilion
White
Porosity
Less Porous
Highly Porous
Luster
Resinous
Shiny
Compressive Strength
206.00 N/mm2150.00 N/mm2
0.15
450
👆🏻
Cleavage
-
Slaty
Toughness
-
1.5
Specific Gravity
2.42.5-2.9
0
8.4
👆🏻
Transparency
Opaque
Opaque
Density
3.058 g/cm32.8-2.9 g/cm3
0
1400
👆🏻
Thermal Properties
Specific Heat Capacity
0.56 kJ/Kg K0.70 kJ/Kg K
0.14
3.2
👆🏻
Resistance
Heat Resistant, Impact Resistant, Wear Resistant
Impact Resistant, Pressure Resistant, Water Resistant
Deposits in Eastern Continents
Asia
Cambodia, Russia, South Korea
Afghanistan, Bangladesh, Bhutan, China, India, Japan, Kazakhstan, Malaysia, Pakistan, Russia, Thailand, Turkey, Vietnam
Africa
East Africa
Egypt, Ethiopia, Morocco, Nigeria, South Africa
Europe
England, Germany, Hungary, Iceland, Scotland, Sweden
Austria, England, France, Georgia, Germany, Italy, Liechtenstein, Monaco, Norway, Slovenia, Spain, Sweden, Switzerland
Others
Hawaii Islands
-
Deposits in Western Continents
North America
USA
Canada, Costa Rica, Cuba, Mexico, Panama, USA
South America
-
Brazil, Colombia, Guyana
Deposits in Oceania Continent
Australia
Victoria
New South Wales, New Zealand, Queensland