Definition
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks
Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
Discoverer
Unknown
Unknown
Etymology
From the Middle High German verb gneist (to spark; so called because the rock glitters)
From German Tachylite, from tachy- + Greek lutos soluble, melting
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Other Categories
Coarse Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Banded, Foliated, Platy
Vitreous
Color
Black, Brown, Pink, Red, White
Black, Dark Brown
Durability
Durable
Durable
Appearance
Foliated
Glassy
Interior Uses
Countertops, Decorative Aggregates, Flooring, Interior Decoration
Decorative Aggregates, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone
Cutting Tool, Knives, Landscaping, Scrapers
Antiquity Uses
Artifacts
Artifacts
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
Cemetery Markers, Creating Artwork
Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
Volcanic glass
Features
Generally rough to touch, Is one of the oldest rock
Available in Lots of Colors and Patterns, Clasts are smooth to touch
Archaeological Significance
Famous Monuments
Konark Sun Temple in India, Washington Monument, US
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Formation
Gneiss is a high grade metamorphic rock i.e. it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of Gneiss forms from volcanic rock, shale or granitie.
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.
Mineral Content
Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon
Feldspar, Olivine
Compound Content
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide
Fe, Mg
Types of Metamorphism
Impact Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Biological Weathering, Mechanical Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Medium to Coarse Grained
Medium to Fine Coarse Grained
Fracture
Irregular
Conchoidal
Porosity
Very Less Porous
Less Porous
Specific Gravity
2.5-2.7
2.4
Transparency
Translucent to Opaque
Opaque
Density
2.6-2.9 g/cm3
3.058 g/cm3
Resistance
Heat Resistant, Pressure Resistant, Scratch Resistant, Wear Resistant
Heat Resistant, Impact Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Iraq, Kazakhstan, Kyrgyzstan, Mongolia, Russia
Cambodia, Russia, South Korea
Africa
Cameroon, Ethiopia, Ghana, Kenya, Madagascar, Morocco, Mozambique, Namibia, Nigeria, Tanzania, Togo
East Africa
Europe
Albania, Austria, Bosnia and Herzegovina, Finland, France, Georgia, Germany, Hungary, Italy, Kosovo, Monaco, Norway, Poland, Romania, Serbia, Slovakia, Slovenia, Switzerland, Ukraine, United Kingdom
England, Germany, Hungary, Iceland, Scotland, Sweden
Deposits in Western Continents
North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
USA
South America
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
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Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Victoria
Victoria
Gneiss vs Tachylite 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. Gneiss vs Tachylite characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Gneiss and Properties of Tachylite. Learn more about Gneiss vs Tachylite in the next section. The interior uses of Gneiss include Countertops, Decorative aggregates, Flooring and Interior decoration whereas the interior uses of Tachylite include Decorative aggregates and Interior decoration. Due to some exceptional properties of Gneiss and Tachylite, they have various applications in construction industry. The uses of Gneiss in construction industry include As dimension stone and that of Tachylite include Cutting tool, Knives, Landscaping, Scrapers.
More about Gneiss and Tachylite
Here you can know more about Gneiss and Tachylite. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Gneiss and Tachylite consists of mineral content and compound content. The mineral content of Gneiss includes Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon and mineral content of Tachylite includes Feldspar, Olivine. You can also check out the list of all Metamorphic Rocks. When we have to compare Gneiss vs Tachylite, the texture, color and appearance plays an important role in determining the type of rock. Gneiss is available in black, brown, pink, red, white colors whereas, Tachylite is available in black, dark brown colors. Appearance of Gneiss is Foliated and that of Tachylite is Glassy. Properties of rock is another aspect for Gneiss vs Tachylite. The hardness of Gneiss is 7 and that of Tachylite is 5.5. The types of Gneiss are Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss. whereas types of Tachylite are Volcanic glass. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Gneiss is white while that of Tachylite is vermilion. The specific heat capacity of Gneiss is 0.70 kJ/Kg K and that of Tachylite is 0.56 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Gneiss is heat resistant, pressure resistant, scratch resistant, wear resistant whereas Tachylite is heat resistant, impact resistant, wear resistant.