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
Essexite which is also known as nepheline monzogabbro, is a dark gray or black holocrystalline plutonic Iigneous Rock
Discoverer
Unknown
Unknown
Etymology
From German which means hornstone
From the locality in Essex County, Massachusetts,US
Class
Metamorphic Rocks
Igneous Rocks
Sub-Class
Durable Rock, Soft Rock
Durable Rock, Hard Rock
Group
Not Applicable
Plutonic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock
Texture
Granular, Platy
Granular
Color
Brown, Dark Greenish - Grey, Green, Reddish Brown
Dark Grey to Black
Durability
Durable
Durable
Interior Uses
Decorative Aggregates, Flooring, Homes, Interior Decoration
Decorative Aggregates, Homes, Interior Decoration
Exterior Uses
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
As Building Stone, As Facing Stone, Garden Decoration, Office Buildings, Paving Stone
Other Architectural Uses
Curbing
Curbing
Construction Industry
for Road Aggregate, Roadstone
As Dimension Stone, Building houses or walls, Cement Manufacture, Construction Aggregate, for Road Aggregate
Medical Industry
Not Yet Used
Not Yet Used
Antiquity Uses
Artifacts, Monuments
Artifacts, Monuments, Sculpture, Small Figurines
Commercial Uses
Cemetery Markers, Commemorative Tablets, Creating Artwork
Cemetery Markers, Commemorative Tablets, Jewelry, Sea Defence, Tombstones
Types
Biotite hornfels
Not Available
Features
Smooth to touch
Is one of the oldest rock, Smooth to touch
Archaeological Significance
Famous Monuments
Data Not Available
Data Not Available
Sculpture
Not Yet Used
Used
Famous Sculptures
Not Applicable
Data Not Available
Pictographs
Used
Not Used
Petroglyphs
Used
Not Used
Figurines
Not Yet Used
Used
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.
Essexite is a type of igneous rock, which is usually dark grey to black plutonic rock. For the formation of essexite, suitable magma with exact composition of K, Ba, Rb, Cs, Sr should be produced.
Mineral Content
Andalusite
Augite, Feldspar, Hornblende, Nepheline, Olivine, Plagioclase, Pyroxene
Compound Content
Fe, Mg
Aluminium Oxide, Ba, Ca, Cs, Potassium, Rb, Sodium, Sr
Types of Metamorphism
Not Applicable
Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism, Hydrothermal Metamorphism, Impact Metamorphism
Types of Weathering
Biological Weathering
Biological Weathering, Chemical Weathering
Types of Erosion
Chemical Erosion, Glacier Erosion, Sea Erosion, Water Erosion, Wind Erosion
Coastal Erosion, Glacier Erosion, Water Erosion
Grain Size
Fine Grained
Fine Grained
Fracture
Conchoidal
Conchoidal
Porosity
Highly Porous
Highly Porous
Luster
Shiny
Not Available
Compressive Strength
Not Available
Cleavage
Perfect
Not Available
Toughness
Not Yet Found
1.6
Specific Gravity
3.4-3.9
Not Available
Transparency
Opaque
Opaque
Density
0.25-0.30 g/cm3
Not Available
Specific Heat Capacity
Not Available
Resistance
Heat Resistant, Impact Resistant, Pressure Resistant
Impact Resistant, Pressure Resistant, Wear Resistant
Deposits in Eastern Continents
Asia
Bangladesh, Bhutan, China, India, North Korea, Qatar, Russia, Saudi Arabia, South Korea, Thailand
India, Russia
Africa
Cameroon, East Africa, Tanzania, Western Africa
South Africa
Europe
United Kingdom
Germany, Greece, Italy, Scotland, Turkey
Others
Not Yet Found
Greenland
Deposits in Western Continents
North America
Canada, USA
Canada, USA
South America
Bolivia, Brazil, Colombia, Ecuador
Brazil, Colombia, Venezuela
Deposits in Oceania Continent
Australia
New South Wales, New Zealand, Queensland, Western Australia
New Zealand, Queensland