Definition
It is a metamorphic magnesium rich rock because it is composed of the mineral talc
Trondhjemite is a leucocratic (light-colored) intrusive igneous rock. It is a variety of tonalite in which the plagioclase is mostly in the form of oligoclase. Trondhjemites are sometimes known as plagiogranites.
Discoverer
Unknown
Unknown
Etymology
From 17th century, because of its greasy feel and use like a soap
Not Available
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Group
Not Applicable
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Polished
Phaneritic
Color
Black, Black to Grey, Green, Grey
Black, Brown, Light to Dark Grey, White
Durability
Durable
Durable
Appearance
Dull, Banded and Foilated
Banded and Foilated
Interior Uses
Bathrooms, Decorative Aggregates, Homes, Interior Decoration
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
Exterior Uses
As Facing Stone, Garden Decoration
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Construction Industry
Manufacture of Magnesium and Dolomite Refractories
As Dimension Stone, Cement Manufacture, Cobblestones, Construction Aggregate, for Road Aggregate
Medical Industry
Taken as a Supplement for Calcium or Magnesium
Not Yet Used
Antiquity Uses
Artifacts, Jewellery, Monuments, Sculpture
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Creating Artwork, Gemstone, Jewelry, Manufacture of Soap, Solvents, Dyes, Plastics and Fibres, Production of Lime, Source of Magnesia (MgO)
Cemetery Markers, Creating Artwork
Types
Not Available
Not Available
Features
Host Rock for Lead
Is one of the oldest rock, Typically speckled black and white.
Archaeological Significance
Monuments
Used
Not Yet Used
Famous Monuments
Christ the Redeemer in Rio de Janeiro, Stonehenge in English county of Wiltshire
Not Applicable
Famous Sculptures
Data Not Available
Data Not Available
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Formation
Soapstone is a talc-schist, which is a type of metamorphic rock and it is largely composed of the mineral talc and is thus rich inmagnesium.
When alkali feldspar is extracted from granite, it changes to granitoid and later, it becomes trondhjemite with quartz as major mineral.
Mineral Content
Albite, Apatite, Biotite, Calcite, Carbonate, Clay Minerals, Hornblende, Ilmenite, Micas, Plagioclase, Pyroxene, Quartz
Albite, Amphibole, Apatite, Biotite, Feldspar, Hornblade, Ilmenite, Magnetite, Manganese Oxides, Olivine, Plagioclase, Pyroxene, Quartz, Sulfides, Titanite, Zircon
Compound Content
CaO, Mg, MgO
NaCl, CaO, MgO, Silicon Dioxide
Types of Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
Not Applicable
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Not Applicable
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Grain Size
Fine Grained
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Streak
Black
Bluish Black
Porosity
Less Porous
Very Less Porous
Luster
Greasy
Subvitreous to Dull
Compressive Strength
Not Available
Cleavage
Perfect
Not Available
Specific Gravity
2.86
2.86-3
Transparency
Opaque
Opaque
Density
2.8-2.9 g/cm3
2.73 g/cm3
Resistance
Heat Resistant, Pressure Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
China, India, Indonesia, Japan, North Korea, Russia, Saudi Arabia, Singapore, South Korea, Sri Lanka, Tajikistan, Thailand
Not Yet Found
Africa
Egypt, Ethiopia, Ghana, South Africa, Western Africa
Egypt
Europe
Austria, England, Finland, France, Germany, Greece, Spain, Sweden, Switzerland, United Kingdom
Finland, Germany, Italy, Romania, Sweden, Turkey
Others
Not Yet Found
Not Yet Found
Deposits in Western Continents
North America
Canada, USA
USA
South America
Colombia
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
Central Australia, New Zealand, Queensland
New Zealand, South Australia, Western Australia