Schist

Dacite

Schist and Dacite

Schist

Dacite

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Definition

Schist is a medium grade metamorphic rock with medium to large, flat, sheet like grains in a preferred orientation

Dacite is a volcanic igneous rock which is rintermediate in composition between andesite and rhyolite

History

Origin

Romania and Moldova, Europe

Discoverer

Unknown

Etymology

From French schiste, Greek skhistos i.e. split

From Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains where the rock was first described

Class

Metamorphic Rocks

Igneous Rocks

Sub-Class

Durable Rock, Medium Hardness Rock

Durable Rock, Soft Rock

Family

Group

Volcanic

Other Categories

Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Texture

Foliated, Platy

Aphanitic to Porphyritic

Color

Black, Blue, Brown, Dark Brown, Green, Grey, Silver

Bluish - Grey, Brown, Grey, Light to Dark Grey

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Layered and Shiny

Vesicular

Uses

Architecture

Interior Uses

Decorative Aggregates, Floor Tiles, Interior Decoration

Decorative Aggregates, Entryways, Interior Decoration

Exterior Uses

Garden Decoration, Paving Stone

As Building Stone, Paving Stone, Garden Decoration

Other Architectural Uses

Curbing

Industry

Construction Industry

As Dimension Stone, Building houses or walls, Cement Manufacture, for Road Aggregate, Roadstone

As Dimension Stone, Construction Aggregate, for Road Aggregate, Landscaping

Medical Industry

Antiquity Uses

Artifacts

Other Uses

Commercial Uses

Used in aquariums, Writing Slates

Commemorative Tablets, Creating Artwork

Types

Mica Schists, Calc-Silicate Schists, Graphite Schists, Blueschists, Whiteschists, Greenschists, Hornblende Schist, Talc Schist, Chlorite Schist, Garnet Schist, Glaucophane schist.

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

Features

Easily splits into thin plates, Smooth to touch

Host Rock for Lead, Is one of the oldest rock

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Formation

Schist formed by dynamic metamorphism at high temperatures and pressures that aligns the grains of mica, hornblende and other elongated minerals into thin layers.

Dacitic magma is formed by the subduction of young oceanic crust under a thick felsic continental plate. Further, the Oceanic crust is hydrothermally altered as quartz and sodium are added.

Composition

Mineral Content

Alusite, Amphibole, Biotite, Chlorite, Epidote, Feldspar, Garnet, Graphite, Hornblade, Kyanite, Micas, Muscovite or Illite, Porphyroblasts, Quartz, Sillimanite, Staurolite, Talc

Amphibole, Apatite, Biotite, Feldspar, Garnet, Hornblade, Magnetite, Plagioclase, Pyroxene, Quartz, Zircon

Compound Content

CaO, Carbon Dioxide, MgO

Ca, Fe, Potassium Oxide, Mg, Potassium, Silicon Dioxide

Transformation

Metamorphism

✔ ✘

Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism

Weathering

✔ ✘

Types of Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

Erosion

✔ ✘

Types of Erosion

Chemical Erosion, Coastal Erosion, Glacier Erosion

Chemical Erosion

Properties

Physical Properties

Hardness

3.5-42-2.25

1 7

👆🏻

Grain Size

Medium to Fine Coarse Grained

Fracture

Conchoidal

Streak

White

Porosity

Highly Porous

Less Porous

Luster

Shiny

Subvitreous to Dull

Compressive Strength

150.00 N/mm²70.00 N/mm²

0.15 450

👆🏻

Cleavage

Slaty

Perfect

Toughness

1.5

Specific Gravity

2.5-2.92.86-2.87

0 8.4

👆🏻

Transparency

Opaque

Translucent

Density

2.8-2.9 g/cm³2.77-2.771 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.70 kJ/Kg K0.92 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Impact Resistant, Pressure Resistant, Water Resistant

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

Afghanistan, Bangladesh, Bhutan, China, India, Japan, Kazakhstan, Malaysia, Pakistan, Russia, Thailand, Turkey, Vietnam

Africa

Egypt, Ethiopia, Morocco, Nigeria, South Africa

Europe

Austria, England, France, Georgia, Germany, Italy, Liechtenstein, Monaco, Norway, Slovenia, Spain, Sweden, Switzerland

France, Greece, Romania, Scotland, Spain

Others

Deposits in Western Continents

North America

Canada, Costa Rica, Cuba, Mexico, Panama, USA

USA

South America

Brazil, Colombia, Guyana

Argentina, Bolivia, Chile, Colombia, Ecuador, Peru, Venezuela

Deposits in Oceania Continent

Australia

New South Wales, New Zealand, Queensland

New Zealand, South Australia, Western Australia

All about Schist and Dacite Properties

Know all about Schist and Dacite properties here. All properties of rocks are important as they define the type of rock and its application. Schist belongs to Metamorphic Rocks while Dacite belongs to Igneous Rocks.Texture of Schist is Foliated, Platy whereas that of Dacite is Aphanitic to Porphyritic. Schist appears Layered and Shiny and Dacite appears Vesicular. The luster of Schist is shiny while that of Dacite is subvitreous to dull. Schist is available in black, blue, brown, dark brown, green, grey, silver colors whereas Dacite is available in bluish - grey, brown, grey, light to dark grey colors. The commercial uses of Schist are used in aquariums, writing slates and that of Dacite are commemorative tablets, creating artwork.