Definition
Tonalite is a coarse-grained plutonic rock consisting mainly of sodic plagioclase, quartz, and hornblende or other mafic minerals with phaneritic texture
Variolites are a group of dark green basic igneous rocks which exhibit pale colored spots, or spherules, especially on weathered surfaces, that give them a pockmarked appearance
Origin
Tonale, Italy
France
Discoverer
Warren Hamilton
Unknown
Etymology
From Tonale Pass, northern Italy, + -ite1
From Latin varius, speckled, variegated
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
Opaque Rock
Texture
Phaneritic
Glassy, Massive, Porphyritic, Scoriaceous, Vesicular
Color
Black, Brown, Light to Dark Grey, White
Black, Brown, Light to Dark Grey
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Banded and Foilated
Dull and Soft
Interior Uses
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
Floor Tiles, Flooring, Homes, Hotels, Kitchens
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Cement Manufacture, Cobblestones, Construction Aggregate, for Road Aggregate
As Dimension Stone, Cobblestones, Rail Track Ballast, Roadstone
Antiquity Uses
Artifacts, Sculpture
Artifacts, Monuments, Sculpture
Commercial Uses
Cemetery Markers, Creating Artwork
Cemetery Markers, Creating Artwork
Types
Dacite
Metamorphic rock
Features
Is one of the oldest rock, Typically speckled black and white.
Has High structural resistance against erosion and climate, Very fine grained rock
Archaeological Significance
Formation
When alkali feldspar is extracted from granite, it changes to granitoid and later, it becomes tonalite with quartz as major mineral.
Variolites are a group of dark green basic igneous rocks that exhibit pale colored spots on weathered surfaces that give them a pockmarked appearance.
Mineral Content
Albite, Amphibole, Apatite, Biotite, Feldspar, Hornblade, Ilmenite, Magnetite, Manganese Oxides, Olivine, Plagioclase, Pyroxene, Quartz, Sulfides, Titanite, Zircon
Olivine, Plagioclase, Pyroxene
Compound Content
NaCl, CaO, MgO, Silicon Dioxide
Aluminium Oxide, CaO, Iron(III) Oxide, FeO, Potassium Oxide, MgO, MnO, Sodium Oxide, Phosphorus Pentoxide, 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, Mechanical Weathering
Types of Erosion
Wind Erosion
-
Grain Size
Medium to Fine Coarse Grained
-
Fracture
Conchoidal
Conchoidal
Streak
Bluish Black
White to Grey
Porosity
Very Less Porous
Less Porous
Luster
Subvitreous to Dull
-
Specific Gravity
2.86-3
2.8-3
Transparency
Opaque
Opaque
Density
2.73 g/cm3
2.9-3.1 g/cm3
Resistance
Heat Resistant, Pressure Resistant, Water Resistant
Heat Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Africa
Egypt
South Africa
Europe
Finland, Germany, Italy, Romania, Sweden, Turkey
Iceland
Deposits in Western Continents
North America
USA
Canada, USA
South America
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru
Brazil
Deposits in Oceania Continent
Australia
New Zealand, South Australia, Western Australia
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