Definition
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
Mudstone is a fine-grained, dark gray sedimentary rock, which is formed from silt and clay and is similar to shale but has less laminations
Discoverer
Alexandre Brongniart and René Just Haüy
William Smith
Etymology
From Greek trakhus rough’ or trakhutēs roughness
From the English mud and stone, from low German mudde and stainaz
Class
Igneous Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Medium Hardness Rock
Durable Rock, Soft Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Aphanitic to Porphyritic
Clastic
Color
Black, Brown, Dark Greenish - Grey, Green, Grey, Light to Dark Grey, White
Black, Blue, Brown, Green, Grey, Orange, Red, White, Yellow
Durability
Durable
Durable
Appearance
Banded
Rough and Dull
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Entryways, Floor Tiles, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Paving Stone, Garden Decoration, Office Buildings
As Building Stone, As Facing Stone, Paving Stone, Roof Tiles
Other Architectural Uses
Curbing
Curbing
Construction Industry
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate, Landscaping, Making natural cement, Manufacture of Magnesium and Dolomite Refractories
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Antiquity Uses
Artifacts, Monuments, Sculpture, Small Figurines
Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Creating Artwork
Creating Artwork, Pottery
Types
Felsic volcanic rock
Marl, Shale and Argillite
Features
Available in Lots of Colors and Patterns, Is one of the oldest rock, Matrix variable
Available in Lots of Colors and Patterns, Smooth to touch, Very fine grained rock
Archaeological Significance
Formation
Trachyte is an igneous volcanic rock with an aphanitic to porphyritic texture. It is the volcanic equivalent of syenite rock and forms as a result of magmatic differentiation.
Mudstone forms when very fine-grained clay particles are deposited in water which settle at the bottom of water bodies. They are buried and compacted by overlying sediment hence forming mudstone.
Mineral Content
Augite, Biotite, Feldspar, Hornblade, Plagioclase, Quartz
Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, Quartz
Compound Content
Potassium Oxide, Sodium Oxide, Silicon Dioxide
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, Silicon Dioxide
Types of Metamorphism
Cataclastic Metamorphism, Contact Metamorphism, Regional Metamorphism
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Types of Weathering
Biological Weathering, Chemical Weathering, Mechanical Weathering
Chemical Weathering, Mechanical Weathering
Types of Erosion
Chemical Erosion, Coastal Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Sea Erosion
Grain Size
Fine Grained
Very fine-grained
Porosity
Less Porous
Highly Porous
Specific Gravity
2.7
2.2-2.8
Transparency
Opaque
Opaque
Density
2.43-2.45 g/cm3
2.4-2.8 g/cm3
Resistance
Heat Resistant, Impact Resistant, Wear Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
China, India, Iran, Saudi Arabia, Sri Lanka, Taiwan, Thailand, Turkey, Vietnam
Bangladesh, China, India, Russia
Africa
Angola, Egypt, Madagascar, Namibia, Nigeria, South Africa
Ethiopia, Kenya, Morocco, South Africa, Tanzania
Europe
Bulgaria, England, Germany, Norway, Romania, Switzerland
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Deposits in Western Continents
South America
Brazil, Chile
Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela
Deposits in Oceania Continent
Australia
New Zealand, Queensland, South Australia, Western Australia
New South Wales, New Zealand, Queensland, Victoria, Western Australia