Gemology – Information

What Is a Gemstone?

The gemstone is just a piece of minerals or crystal that well cut and polished by tools in gemological labs. While Explore of beautiful minerals and gems we found more than 4000 gems that are amazing and attractive by their appearance. Gemstones appearance, luster, hardness, specific gravity, and other physical properties are depending on their internal chemical composition.

A gemstone is a collective term for all ornamental stones that possess the following attributes:

  1. Beauty
  2. Rarity
  3. Durability
  4. Demand
  5. Tradition
  6. Portability

Gemstones have three basic origins:

  1. Inorganic: minerals.
  2. Organic: formed from living organisms.
  3. Man-made: formed in a laboratory environment.

WHAT IS A MINERAL?

A mineral can be defined as being of inorganic origin with a definite chemical composition, physical properties which are relatively constant and a crystalline structure.

In mineralogy, there are several thousand minerals listed, but only about 100 have been cut as gemstones with fewer than 50 having the necessary qualities to be truly classed as “Gemstones”.

WHAT IS ROCK?

A rock can be defined as any mineral or mixture of minerals that make up an important part of the earth’s crust

Rock is a metamorphic rock type that changes its shape with changing heat and pressure. Rock is occurring solid mass and mineraloid matter.

Rock are categories on the basses of its Composition and composed one mineral. Quartz and Pyrite are types of rock that suit the one mineral Composition.

Rock Classification:

Rock is Further classified below on the bases of formation

  1. Metamorphic
  2. Sedimentary
  3. Igneous

Examples:

  • Granite (Feldspar, Quartz, and Mica)
  • Lapis Lazuli: (Lazurite, Sodalite, Calcite, and Pyrite)

There are three main groups of rocks, namely:

1. Igneous –

Igneous rocks Magmatic and Igneous rock is one of the important types from the above three. Igneous(Magmatic) rock is formed from molten rock material by solidification process or you can say Rock solidified from the molten magma either within the earth or at its surface.

Igneous(Magmatic) rock is further divided into two types: (a) Intrusive igneous rocks (b) Extrusive igneous rocks

2. Sedimentary –

Sedimentary rocksFormed from the fine deposits of sand, grit, and clay which were eroded from ancient pre-existing rocks by the actions of wind, rain and flowing water to form alluvial deposits.

3. Metamorphic –

Metamorphic rocksFormed from Igneous or Sedimentary rocks which have been subjected to high pressure and temperatures beneath the earth’s surface.

There are two basic types of metamorphic rocks.
1. Foliated metamorphic rocks
2. Non-foliated metamorphic rocks

Gemstones can be further classified into:

  1. Groups
  2. Species
  3. Varieties
Group Species Variety
Feldspar Beryl Chrysoberyl

Corundum

Orthoclase

Microcline

Plagioclase

 Emerald, Aquamarine, Alexandrite, Chrysoberyl.

Ruby and Sapphire.

Moonstone.

Amazonite.

Labradorite.
Garnet Almandine Pyrope

Grossular

Andradite

Spessartite

Uvarovite

 Purple/ Blood red.

Hessonite.

Demantoid.

Orange, yellow, flame red.

Emerald green.
Opal Quartz

Chalcedony

Tourmaline

 Black Opal, White Opal, Fire Opal, Amethyst, Citrine.

Agates, Cornelian, Onyx.

Indicolite, Rubellite, Green Tourmaline.