Definition
Gossan is intensely oxidized, weathered or decomposed rock, usually the upper and exposed part of an ore deposit or mineral vein.
Tonalite is a coarse-grained plutonic rock consisting mainly of sodic plagioclase, quartz, and hornblende or other mafic minerals with phaneritic texture
Origin
Indonesia
Tonale, Italy
Discoverer
Cornish Gossen
Warren Hamilton
Etymology
From Cornish gossen from gos, blood from Old Cornish guit
From Tonale Pass, northern Italy, + -ite1
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Hard Rock
Other Categories
Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Texture
Rough, Sandy
Phaneritic
Color
Brown, Brown- Black, Gold, Green, Rust
Black, Brown, Light to Dark Grey, White
Durability
Durable
Durable
Scratch Resistant
Yes
Yes
Appearance
Dull and Banded
Banded and Foilated
Interior Uses
Countertops, Decorative Aggregates, Interior Decoration
Decorative Aggregates, Entryways, Flooring, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Cement Manufacture, Construction Aggregate, for Road Aggregate
As Dimension Stone, Cement Manufacture, Cobblestones, Construction Aggregate, for Road Aggregate
Antiquity Uses
Artifacts
Artifacts, Sculpture
Commercial Uses
Cemetery Markers, Commemorative Tablets, Gemstone
Cemetery Markers, Creating Artwork
Types
Translocated gossan and Leakage gossan
Dacite
Features
Clasts are smooth to touch, Easily splits into thin plates
Is one of the oldest rock, Typically speckled black and white.
Archaeological Significance
Formation
Earth movements can cause rocks to be either deeply buried or squeezed and hence the rocks are heated and put under great pressure.
When alkali feldspar is extracted from granite, it changes to granitoid and later, it becomes tonalite with quartz as major mineral.
Mineral Content
Apatite, Augite, Biotite, Bronzite, Calcite, Chert, Epidote, Feldspar, Hornblende, Micas, Plagioclase, Pyroxene, Quartz, Sulfides, Zircon
Albite, Amphibole, Apatite, Biotite, Feldspar, Hornblade, Ilmenite, Magnetite, Manganese Oxides, Olivine, Plagioclase, Pyroxene, Quartz, Sulfides, Titanite, Zircon
Compound Content
Aluminium Oxide, CaO, Fe, FeO, Silicon Dioxide, Sulphur
NaCl, CaO, MgO, Silicon Dioxide
Types of Metamorphism
-
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism, Regional Metamorphism
Types of Weathering
-
Biological Weathering, Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Sea Erosion, Wind Erosion
Wind Erosion
Grain Size
Fine to Medium Grained
Medium to Fine Coarse Grained
Fracture
Conchoidal
Conchoidal
Streak
White to Grey
Bluish Black
Porosity
Highly Porous
Very Less Porous
Luster
Metallic
Subvitreous to Dull
Specific Gravity
2.0
2.86-3
Transparency
Opaque
Opaque
Density
-9999 g/cm3
2.73 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Pressure Resistant, Water Resistant
Deposits in Eastern Continents
Asia
China, India, Indonesia, Russia, Singapore, South Korea
-
Africa
Cape Verde, Ethiopia, Ghana, South Africa, Western Africa
Egypt
Europe
Albania, France, Germany, Great Britain, United Kingdom
Finland, Germany, Italy, Romania, Sweden, Turkey
Deposits in Western Continents
North America
Canada, USA
USA
South America
Brazil, Colombia, Ecuador
Argentina, Bolivia, Chile, Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
New South Wales, South Australia, Western Australia
New Zealand, South Australia, Western Australia