Definition
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
Adakite is an intermediate to felsic volcanic rock that has geochemical characteristics of magma which is said to be formed by partial melting of altered basalt that is subducted below volcanic arcs
Origin
Iceland
Adak, Aleutian Islands
Discoverer
Unknown
Defant and Drummond
Etymology
From German Tachylite, from tachy- + Greek lutos soluble, melting
From Adak, Aleutian Islands
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Medium Hardness Rock
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Vitreous
Porphyritic
Color
Black, Dark Brown
Black, Brown, Light to Dark Grey
Durability
Durable
Durable
Appearance
Glassy
Dull and Soft
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Floor Tiles, Homes, Hotels, Kitchens
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Office Buildings
Other Architectural Uses
Curbing
Whetstones
Construction Industry
Cutting Tool, Knives, Landscaping, Scrapers
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Antiquity Uses
Artifacts
Monuments, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Creating Artwork
Commemorative Tablets, Pottery, Used in aquariums
Types
Volcanic glass
Intermediate volcanic rock
Features
Available in Lots of Colors and Patterns, Clasts are smooth to touch
Has High structural resistance against erosion and climate, Host rock for Diamond, Very fine grained rock
Archaeological Significance
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.
Adakite rocks are formed when the hydrous fluids are released from minerals that break down in metamorphosed basalt, and rise into the mantle they initiate partial melting.
Mineral Content
Feldspar, Olivine
Olivine, Plagioclase, Pyroxene
Compound Content
Fe, Mg
Aluminium Oxide, MgO, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Coastal Erosion, Sea Erosion, Water Erosion
Grain Size
Medium to Fine Coarse Grained
Fine to Medium Grained
Fracture
Conchoidal
Conchoidal
Streak
Vermilion
Bluish Black
Porosity
Less Porous
Less Porous
Luster
Resinous
Grainy, Pearly and Vitreous
Specific Gravity
2.4
-9999
Transparency
Opaque
Opaque
Density
3.058 g/cm3
-9999 g/cm3
Resistance
Heat Resistant, Impact Resistant, Wear Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Cambodia, Russia, South Korea
India, Russia
Africa
East Africa
Ethiopia, Somalia, South Africa
Europe
England, Germany, Hungary, Iceland, Scotland, Sweden
Iceland
Deposits in Western Continents
North America
USA
Canada, USA
Deposits in Oceania Continent