Dacite

Chert

Dacite and Chert

Dacite

Chert

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Definition

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

Chert is a hard, dark, opaque sedimentary rock which is composed of silica with an amorphous fine-grained texture

History

Origin

Romania and Moldova, Europe

Discoverer

Unknown

Etymology

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

From flint-like quartz, 1670s, of unknown origin- a local term, which has been taken into geological use

Class

Igneous Rocks

Sedimentary Rocks

Sub-Class

Durable Rock, Soft Rock

Durable Rock, Hard Rock

Family

Group

Volcanic

Other Categories

Fine Grained Rock, Medium Grained Rock, Opaque Rock

Fine Grained Rock, Opaque Rock

Texture

Aphanitic to Porphyritic

Banded, Rough

Color

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

Black, Brown, Green, Grey, Red, White

Maintenance

Less

Durability

Durable

Water Resistant

✔ ✘

Scratch Resistant

✔ ✘

Stain Resistant

✔ ✘

Wind Resistant

✔ ✘

Acid Resistant

✔ ✘

Appearance

Vesicular

Glassy or Pearly

Uses

Architecture

Interior Uses

Decorative Aggregates, Entryways, Interior Decoration

Decorative Aggregates, Homes

Exterior Uses

As Building Stone, Paving Stone, Garden Decoration

As Building Stone, As Facing Stone, Garden Decoration, Office Buildings

Other Architectural Uses

Curbing

Industry

Construction Industry

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

Arrowheads, Construction Aggregate, Cutting Tool, Spear Points

Medical Industry

Antiquity Uses

Artifacts

Artifacts, Monuments

Other Uses

Commercial Uses

Commemorative Tablets, Creating Artwork

Creating Artwork, Gemstone, In fire-starting tools, Jewelry, To ignite fire, Used in flintlock firearms

Types

Footwall Dacite, Hanging wall Dacite, Tuff and Biotite Dacite

Flint, Jasper, Radiolarite, Common Chert, Chalcedony, Agate, Onyx, Opal, Magadi-type Chert, Porcelanite, Siliceous Sinter

Features

Host Rock for Lead, Is one of the oldest rock

Clasts are smooth to touch, Easily splits into thin plates, Has High structural resistance against erosion and climate

Archaeological Significance

Monuments

Famous Monuments

Sculpture

Famous Sculptures

Pictographs

Petroglyphs

Figurines

Fossils

Absent

Present

Formation

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.

Chert forms when microcrystals of silicon dioxide grow within soft sediments that become limestone or chalk. The chert formation can be either of chemical or biological origin.

Composition

Mineral Content

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

Quartz, Silicon

Compound Content

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

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

Properties

Physical Properties

Hardness

2-2.256.5-7

1 7

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Grain Size

Medium to Fine Coarse Grained

Very fine-grained

Fracture

Conchoidal

Uneven, Splintery or Conchoidal

Streak

White

Porosity

Less Porous

Highly Porous

Luster

Subvitreous to Dull

Waxy and Dull

Compressive Strength

70.00 N/mm²450.00 N/mm²

0.15 450

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Cleavage

Perfect

Toughness

1.5

Specific Gravity

2.86-2.872.5-2.8

0 8.4

👆🏻

Transparency

Translucent

Translucent to Opaque

Density

2.77-2.771 g/cm³2.7 g/cm³

0 1400

👆🏻

Thermal Properties

Specific Heat Capacity

0.92 kJ/Kg K0.74 kJ/Kg K

0.14 3.2

👆🏻

Resistance

Heat Resistant, Impact Resistant, Pressure Resistant, Wear Resistant

Reserves

Deposits in Eastern Continents

Asia

China, India, Iran, Japan, Oman, Russia, Saudi Arabia, Taiwan, Thailand, Vietnam

Africa

Kenya, Morocco, South Africa, Tanzania

Europe

France, Greece, Romania, Scotland, Spain

Austria, France, Greece, Italy, Malta, Poland, Portugal, Serbia, Spain, Sweden, United Kingdom

Others

Greenland, Mid-Atlantic Ridge

Deposits in Western Continents

North America

USA

Canada, Mexico, USA

South America

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

Bolivia, Brazil

Deposits in Oceania Continent

Australia

New Zealand, South Australia, Western Australia

New South Wales, Queensland, South Australia, Western Australia

All about Dacite and Chert Properties

Know all about Dacite and Chert properties here. All properties of rocks are important as they define the type of rock and its application. Dacite belongs to Igneous Rocks while Chert belongs to Sedimentary Rocks.Texture of Dacite is Aphanitic to Porphyritic whereas that of Chert is Banded, Rough. Dacite appears Vesicular and Chert appears Glassy or Pearly. The luster of Dacite is subvitreous to dull while that of Chert is waxy and dull. Dacite is available in bluish - grey, brown, grey, light to dark grey colors whereas Chert is available in black, brown, green, grey, red, white colors. The commercial uses of Dacite are commemorative tablets, creating artwork and that of Chert are creating artwork, gemstone, in fire-starting tools, jewelry, to ignite fire, used in flintlock firearms.