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, 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
Antiquity Uses
Artifacts
Artifacts, Monuments, Sculpture
Commercial Uses
Cemetery Markers, Creating Artwork
Creating Artwork, Gemstone, Jewelry
Types
Volcanic glass
Rhomb Porphyry
Features
Available in Lots of Colors and Patterns, Clasts are smooth to touch
Generally rough to touch, Is one of the oldest rock, Surfaces are often shiny
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.
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
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
Specific Gravity
2.4
2.5-4
Transparency
Opaque
Translucent to Opaque
Density
3.058 g/cm3
2.5-2.52 g/cm3
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
-
Bolivia, Brazil, Colombia, Ecuador, Paraguay
Deposits in Oceania Continent
Australia
Victoria
New South Wales, New Zealand, Western Australia
Tachylite vs Porphyry Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Tachylite vs Porphyry characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Tachylite and Properties of Porphyry. Learn more about Tachylite vs Porphyry in the next section. The interior uses of Tachylite include Decorative aggregates and Interior decoration whereas the interior uses of Porphyry include Decorative aggregates and Interior decoration. Due to some exceptional properties of Tachylite and Porphyry, they have various applications in construction industry. The uses of Tachylite in construction industry include Cutting tool, Knives, Landscaping, Scrapers and that of Porphyry include Construction aggregate.
More about Tachylite and Porphyry
Here you can know more about Tachylite and Porphyry. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Tachylite and Porphyry consists of mineral content and compound content. The mineral content of Tachylite includes Feldspar, Olivine and mineral content of Porphyry includes Biotite, Chert, Feldspar, Garnet, Graphite, Quartz, Silica. You can also check out the list of all Igneous Rocks. When we have to compare Tachylite vs Porphyry, the texture, color and appearance plays an important role in determining the type of rock. Tachylite is available in black, dark brown colors whereas, Porphyry is available in black, brown, green, grey, red, rust, white colors. Appearance of Tachylite is Glassy and that of Porphyry is Dull. Properties of rock is another aspect for Tachylite vs Porphyry. The hardness of Tachylite is 5.5 and that of Porphyry is 6-7. The types of Tachylite are Volcanic glass whereas types of Porphyry are Rhomb Porphyry. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Tachylite is vermilion while that of Porphyry is white. The specific heat capacity of Tachylite is 0.56 kJ/Kg K and that of Porphyry is 0.71 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Tachylite is heat resistant, impact resistant, wear resistant whereas Porphyry is heat resistant, impact resistant.