Definition
Hornfels is a metamorphic rock formed by the contact between mudstone or other clay rich rock, and a hot igneous body, and represents a heat altered equivalent of the original rock
Marl is an unconsolidated sedimentary rock consisting of clay and lime
Discoverer
Unknown
William Smith
Etymology
From German which means hornstone
From Old French marle, from Late Latin marglia
Class
Metamorphic Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Soft Rock
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Granular, Platy
Earthy
Color
Brown, Dark Greenish - Grey, Green, Reddish Brown
Beige, Brown, Green, Grey, White
Durability
Durable
Durable
Appearance
Dull
Rough and Dull
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Floor Tiles
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, Roof Tiles
Other Architectural Uses
Curbing
Curbing
Construction Industry
for Road Aggregate, Roadstone
Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
Antiquity Uses
Artifacts, Monuments
Artifacts, Jewellery, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork
Creating Artwork, Soil Conditioner
Types
Biotite hornfels
Clay Marl ,Blue Marl, Red Marl, High Bank Marl, Shell Layer Marl, Under Shell Layer Marl, Sand Marl, Green Marl, Grey Marl and Clayey Marl
Features
Smooth to touch
Generally rough to touch, Is one of the oldest rock, Splintery, Very fine grained rock
Archaeological Significance
Formation
Due to change in environmental conditions, rocks are heated and pressurized deep inside the Earth's surface. Hornfels is formed from the extreme heat caused by magma or by the intense collisions and friction of tectonic plates.
Marl forms when very fine-grained clay particles are deposited in water which settles at the bottom of water bodies and are compacted by overlying sediment; the water squeezes out and hence forming Marl rock.
Mineral Content
Andalusite
Calcite, Clay, Dolomite, Gypsum, Micas, Pyrite, Quartz
Compound Content
Fe, Mg
Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, Silicon Dioxide
Types of Metamorphism
-
-
Types of Weathering
Biological Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Chemical Erosion, Coastal Erosion, Water Erosion, Wind Erosion
Grain Size
Fine Grained
Very fine-grained
Fracture
Conchoidal
Conchoidal
Porosity
Highly Porous
Highly Porous
Specific Gravity
3.4-3.9
2.2-2.8
Transparency
Opaque
Opaque
Density
0.25-0.30 g/cm3
2.4-2.8 g/cm3
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Heat Resistant, Impact Resistant
Deposits in Eastern Continents
Asia
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
India, Pakistan, Russia
Africa
Cameroon, East Africa, Tanzania, Western Africa
Ethiopia, Kenya, Morocco, South Africa
Europe
United Kingdom
Austria, France, Germany, Greece, Italy, Romania, Scotland, Spain, Switzerland
Deposits in Western Continents
North America
Canada, USA
USA
South America
Bolivia, Brazil, Colombia, Ecuador
Colombia, Ecuador, Peru
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Western Australia
New South Wales, Victoria, Western Australia
Hornfels vs Marl Characteristics
Though some rocks look identical, they have certain characteristics which distinguish them from others. Characteristics of rocks include texture, appearance, color, fracture, streak, hardness etc. Hornfels vs Marl characteristics assist us to distinguish and recognize rocks. Also you can check about Properties of Hornfels and Properties of Marl. Learn more about Hornfels vs Marl in the next section. The interior uses of Hornfels include Decorative aggregates, Flooring, Homes and Interior decoration whereas the interior uses of Marl include Decorative aggregates and Floor tiles. Due to some exceptional properties of Hornfels and Marl, they have various applications in construction industry. The uses of Hornfels in construction industry include For road aggregate, Roadstone and that of Marl include Cement manufacture, Construction aggregate, For road aggregate, Making natural cement, Raw material for the manufacture of mortar.
More about Hornfels and Marl
Here you can know more about Hornfels and Marl. The life cycle of a rock consists of formation of rock, composition of rock and transformation of rock. The composition of Hornfels and Marl consists of mineral content and compound content. The mineral content of Hornfels includes Andalusite and mineral content of Marl includes Calcite, Clay, Dolomite, Gypsum, Micas, Pyrite, Quartz. You can also check out the list of all Metamorphic Rocks. When we have to compare Hornfels vs Marl, the texture, color and appearance plays an important role in determining the type of rock. Hornfels is available in brown, dark greenish - grey, green, reddish brown colors whereas, Marl is available in beige, brown, green, grey, white colors. Appearance of Hornfels is Dull and that of Marl is Rough and Dull. Properties of rock is another aspect for Hornfels vs Marl. Hardness of Hornfels and Marl is 2-3. The types of Hornfels are Biotite hornfels whereas types of Marl are Clay Marl ,Blue Marl, Red Marl, High Bank Marl, Shell Layer Marl, Under Shell Layer Marl, Sand Marl, Green Marl, Grey Marl and Clayey Marl. Streak of rock is the color of powder produced when it is dragged across an unweathered surface. The streak of Hornfels is while that of Marl is white. The specific heat capacity of Hornfels is 0.84 kJ/Kg K and that of Marl is 0.80 kJ/Kg K. Depending on the properties like hardness, toughness, specific heat capacity, porosity etc., rocks are resistant to heat, wear, impact, etc.Hornfels is heat resistant, impact resistant, pressure resistant whereas Marl is heat resistant, impact resistant.