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
  
History
  
  
Origin
Unknown
  
Iceland
  
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
  
Family
  
  
Group
Not Applicable
  
Volcanic
  
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
  
Maintenance
More
  
More
  
Durability
Durable
  
Durable
  
Water Resistant
Yes
  
Yes
  
Scratch Resistant
Yes
  
No
  
Stain Resistant
Yes
  
No
  
Wind Resistant
Yes
  
Yes
  
Acid Resistant
No
  
Yes
  
Appearance
Foliated
  
Glassy
  
Architecture
  
  
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
  
Industry
  
  
Construction Industry
As Dimension Stone
  
Cutting Tool, Knives, Landscaping, Scrapers
  
Medical Industry
Not Yet Used
  
Not Yet Used
  
Antiquity Uses
Artifacts
  
Artifacts
  
Other Uses
  
  
Commercial Uses
Cemetery Markers, Jewelry, Tombstones, Used in aquariums
  
Cemetery Markers, Creating Artwork
  
Types
Augen Gneiss, Henderson Gneiss, Lewisian Gneiss, Archean and Proterozoic Gneiss.
  
Not Available
  
Features
Generally rough to touch, Is one of the oldest rock
  
Available in Lots of Colors and Patterns, Clasts are smooth to touch, NA
  
Archaeological Significance
  
  
Monuments
Used
  
Not Yet Used
  
Famous Monuments
Konark Sun Temple in India, Washington Monument, US
  
Not Applicable
  
Sculpture
Not Yet Used
  
Not Yet Used
  
Famous Sculptures
Not Applicable
  
Not Applicable
  
Pictographs
Not Used
  
Used
  
Petroglyphs
Not Used
  
Used
  
Figurines
Not Yet Used
  
Not Yet Used
  
Fossils
Absent
  
Absent
  
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.
  
Composition
  
  
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
  
Transformation
  
  
Metamorphism
Yes
  
Yes
  
Types of Metamorphism
Impact Metamorphism
  
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
  
Weathering
Yes
  
Yes
  
Types of Weathering
Biological Weathering, Mechanical Weathering
  
Biological Weathering, Chemical Weathering, Mechanical Weathering
  
Erosion
Yes
  
Yes
  
Types of Erosion
Chemical Erosion, Coastal Erosion, Sea Erosion
  
Chemical Erosion, Sea Erosion, Water Erosion, Wind Erosion
  
Physical Properties
  
  
Hardness
7
  
5.5
  
Grain Size
Medium to Coarse Grained
  
Medium to Fine Coarse Grained
  
Fracture
Irregular
  
Conchoidal
  
Streak
White
  
Vermilion
  
Porosity
Very Less Porous
  
Less Porous
  
Luster
Dull
  
Resinous
  
Compressive Strength
125.00 N/mm2
  
17
206.00 N/mm2
  
8
Cleavage
Poor
  
Not Available
  
Toughness
1.2
  
Not Available
  
Specific Gravity
2.5-2.7
  
2.4
  
Transparency
Translucent to Opaque
  
Opaque
  
Density
2.6-2.9 g/cm3
  
3.058 g/cm3
  
Thermal Properties
  
  
Specific Heat Capacity
Not Available
  
0.56 kJ/Kg K
  
22
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
  
Others
Not Yet Found
  
Hawaii Islands
  
Deposits in Western Continents
  
  
North America
Canada, Costa Rica, Cuba, Mexico, Panama, USA
  
USA
  
South America
Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Venezuela
  
Not Yet Found
  
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 Not Available. 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 Not Available 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.