Definition
Tephrite is an aphanitic to porphyritic textured, volcanic igneous rock
Tonalite is a coarse-grained plutonic rock consisting mainly of sodic plagioclase, quartz, and hornblende or other mafic minerals with phaneritic texture
Origin
Germany
Tonale, Italy
Discoverer
Van Tooren
Warren Hamilton
Etymology
From Greek tephra, ashes from Indo-European base, to burn
From Tonale Pass, northern Italy, + -ite1
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Other Categories
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Aphanitic to Porphyritic
Phaneritic
Color
Black, Brown, Green, Grey, White
Black, Brown, Light to Dark Grey, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Vesicular
Banded and Foilated
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Construction Industry
Landscaping
As Dimension Stone, Cement Manufacture, Cobblestones, Construction Aggregate, for Road Aggregate
Antiquity Uses
Artifacts, Sculpture
Artifacts, Sculpture
Commercial Uses
Production of Lime, Soil Conditioner
Cemetery Markers, Creating Artwork
Types
Igneous rock
Dacite
Features
Host Rock for Lead
Is one of the oldest rock, Typically speckled black and white.
Archaeological Significance
Formation
Tephrite 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.
When alkali feldspar is extracted from granite, it changes to granitoid and later, it becomes tonalite with quartz as major mineral.
Mineral Content
Alkali feldspar, Nepheline, Plagioclase, Pyroxene
Albite, Amphibole, Apatite, Biotite, Feldspar, Hornblade, Ilmenite, Magnetite, Manganese Oxides, Olivine, Plagioclase, Pyroxene, Quartz, Sulfides, Titanite, Zircon
Compound Content
CaO, Carbon Dioxide, MgO, Silicon Dioxide
NaCl, CaO, MgO, Silicon Dioxide
Types of Metamorphism
Cataclastic Metamorphism, Contact 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, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion
Wind Erosion
Grain Size
Medium to Fine Coarse Grained
Medium to Fine Coarse Grained
Fracture
Uneven
Conchoidal
Streak
Bluish Black
Bluish Black
Porosity
Very Less Porous
Very Less Porous
Luster
Subvitreous to Dull
Subvitreous to Dull
Cleavage
Crenulation and Pervasive
-
Specific Gravity
2.86
2.86-3
Transparency
Opaque
Opaque
Density
2.8-2.9 g/cm3
2.73 g/cm3
Resistance
Heat Resistant, Impact Resistant
Heat Resistant, Pressure Resistant, Water Resistant
Deposits in Eastern Continents
Africa
Namibia, Uganda
Egypt
Europe
Germany, Hungary, Italy, Portugal, Spain
Finland, Germany, Italy, Romania, Sweden, Turkey
Deposits in Western Continents
South America
-
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
New Zealand, Western Australia
New Zealand, South Australia, Western Australia