Definition
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
Porphyry is a reddish-brown to purple igneous rock containing large phenocrysts of various minerals embedded in a fine-grained matrix
Discoverer
Unknown
Unknown
Etymology
From German Tachylite, from tachy- + Greek lutos soluble, melting
From Old French porfire, from Italian porfiro and in some cases directly from Latin porphyrites
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Vitreous
Porphyritic
Color
Black, Dark Brown
Black, Brown, Colourless, Green, Grey, Red, Rust, White
Durability
Durable
Durable
Interior Uses
Decorative Aggregates, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
Cutting Tool, Knives, Landscaping, Scrapers
Construction Aggregate
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture
Commercial Uses
Cemetery Markers, Creating Artwork
Creating Artwork, Gemstone, Jewelry
Types
Not Available
Rhomb Porphyry
Features
Available in Lots of Colors and Patterns, Clasts are smooth to touch, NA
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
Archaeological Significance
Monuments
Not Yet Used
Used
Famous Monuments
Not Applicable
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Not Yet Used
Used
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.
Porphyry is formed in two stages: the magma cools slowly deep within the crust or the magma is cools rapidly as it erupts from a volcano, creating small grains that are usually invisible to naked eye.
Mineral Content
Feldspar, Olivine
Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica
Compound Content
Fe, Mg
Aluminium Oxide, CaO, Iron(III) Oxide, Potassium Oxide, MgO, Sodium Oxide, Silicon Dioxide, Titanium Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Not Registered
Types of Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion
Grain Size
Medium to Fine Coarse Grained
Fine Grained
Fracture
Conchoidal
Irregular
Porosity
Less Porous
Less Porous
Compressive Strength
Not Available
Cleavage
Not Available
Imperfect
Toughness
Not Available
1.7
Specific Gravity
2.4
2.5-4
Transparency
Opaque
Translucent to Opaque
Density
3.058 g/cm3
2.5-2.52 g/cm3
Specific Heat Capacity
Not Available
Resistance
Heat Resistant, Impact Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
Cambodia, Russia, South Korea
China, Kazakhstan, South Korea, Thailand, Turkey, Vietnam
Africa
East Africa
Egypt, Ethiopia, Ghana, South Africa
Europe
England, Germany, Hungary, Iceland, Scotland, Sweden
Finland, France, Germany, Great Britain, Hungary, Iceland, Ireland, Italy, Netherlands, Norway, Romania, Sweden, Switzerland
Others
Hawaii Islands
Greenland
Deposits in Western Continents
North America
USA
Canada, Cuba, Jamaica, USA
South America
Not Yet Found
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
Victoria
New South Wales, New Zealand, Western Australia