Tachylite and Dacite
Definition
Definition
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite
History
Origin
Iceland
Romania and Moldova, Europe
Discoverer
Unknown
Unknown
Etymology
From German Tachylite, from tachy- + Greek lutos soluble, melting
From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Family
Group
Volcanic
Volcanic
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Texture
Vitreous
Aphanitic to Porphyritic
Color
Black, Dark Brown
Bluish - Grey, Brown, Grey, Light to Dark Grey
Maintenance
More
Less
Durability
Durable
Durable
Water Resistant
Yes
No
Scratch Resistant
No
No
Stain Resistant
No
No
Wind Resistant
Yes
No
Acid Resistant
Yes
No
Appearance
Glassy
Vesicular
Uses
Architecture
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Entryways, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, Paving Stone, Garden Decoration
Other Architectural Uses
Curbing
Curbing
Industry
Construction Industry
Cutting Tool, Knives, Landscaping, Scrapers
As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts
Other Uses
Commercial Uses
Cemetery Markers, Creating Artwork
Commemorative Tablets, Creating Artwork
Types
Types
Not Available
Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite
Features
Available in Lots of Colors and Patterns, Clasts are smooth to touch, NA
Host Rock for Lead, Is one of the oldest rock
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
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.
Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.
Composition
Mineral Content
Feldspar, Olivine
Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon
Compound Content
Fe, Mg
Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide
Transformation
Metamorphism
Yes
Yes
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism
Weathering
Yes
Yes
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Erosion
Yes
Yes
Types of Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion
Properties
Physical Properties
Hardness
5.5
2-2.25
Grain Size
Medium to Fine Coarse Grained
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Streak
Vermilion
White
Porosity
Less Porous
Less Porous
Luster
Resinous
Subvitreous to Dull
Compressive Strength
206.00 N/mm2
8
Not Available
Cleavage
Not Available
Perfect
Toughness
Not Available
Not Available
Specific Gravity
2.4
2.86-2.87
Transparency
Opaque
Translucent
Density
3.058 g/cm3
2.77-2.771 g/cm3
Thermal Properties
Specific Heat Capacity
0.56 kJ/Kg K
22
0.92 kJ/Kg K
10
Resistance
Heat Resistant, Impact Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant
Reserves
Deposits in Eastern Continents
Asia
Cambodia, Russia, South Korea
Not Yet Found
Africa
East Africa
Not Yet Found
Europe
England, Germany, Hungary, Iceland, Scotland, Sweden
France, Greece, Romania, Scotland, Spain
Others
Hawaii Islands
Not Yet Found
Deposits in Western Continents
North America
USA
USA
South America
Not Yet Found
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
Victoria
New Zealand, South Australia, Western Australia
All about Tachylite and Dacite Properties
Know all about Tachylite and Dacite properties here. All properties of rocks are important as they define the type of rock and its application. Tachylite and Dacite belong to Igneous Rocks.Texture of Tachylite is Vitreous whereas that of Dacite is Aphanitic to Porphyritic. Tachylite appears Glassy and Dacite appears Vesicular. The luster of Tachylite is resinous while that of Dacite is subvitreous to dull. Tachylite is available in black, dark brown colors whereas Dacite is available in bluish - grey, brown, grey, light to dark grey colors. The commercial uses of Tachylite are cemetery markers, creating artwork and that of Dacite are commemorative tablets, creating artwork.
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