Spinel

Spinel is a gorgeous crystalline mineral which occurs in a range of colours. It is prized by collectors for its unusual octahedral formations, and by jewellers for its clarity, colour, and relative hardness.

The name ‘Spinel’ also refers to a larger group of minerals; however, this page refers to the magnesium/aluminium mineral known as Spinel. More detail at the bottom of the page!

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Appearance, Uses and History

The name Spinel is a little confusing, as it can refer to two things. One is the ‘spinel group’, the other is what most people will think of when they hear the name Spinel.

Specifically, Spinel is the magnesium/aluminium member of the Spinel group. Have I lost you yet?

The mineral known as Spinel is used as a gemstone and occurs with an extremely unusual crystalline formation. It typically occurs in crystal octahedrons, although there are other forms.

Locales

Spinel crystals are found in a range of locations, including Afghanistan, Canada, Finland, Germany, Italy, Kenya, Madagascar, Myanmar, Pakistan, Russia, Sri Lanka, Tajikistan, Tanzania, the USA, and Vietnam.

There are other locales, although the crystals are typically less high quality than the ones listed above.

Mineralogy

Chemistry
The Magnesium/Aluminium member of the Spinel group, with the chemical formula MgAl2O4.
Colours and Variations
Red, pink, blue, lavender, dark green, browns, colourless, clear.
Streak
White
Luster
Vitreous to subadmantine.
Fracture
Conchoidal
Transparency
Transparent, translucent, opaque
Crystal habit
Often octahedral or twinned masses of octahedra. Sometimes granular.
Mohs hardness
7.5 – 8.0
Specific Gravity
3.58 – 4.10
Fluorescence
Sometimes fluorescent, but synthetic Spinel is too, so it should not be considered diagnostic.
Easiest testing method
Common Treatments
Sometimes heat treated.

Hazards and Warnings

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.

When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

Translations

Arabic:

  • الإسبنيل

Hindi:

Portuguese:

  • Espinela
  • espinélio

Bengali:

  • লোহিতক

Indonesian:

Punjabi:

English:

  • spinel
  • spinel group

Italian:

  • Gruppo degli spinelli

Russian:

  • Шпинель

French:

  • spinelle

Japanese:

  • スピネル
  • 苦土尖晶石

Spanish:

  • Espinela

German:

  • Spinell

Korean:

  • 스피넬
  • 첨정석

Thai:

Gujurati:

  • સ્પિનલ

Mandarin and Traditional Chinese:

  • 尖晶石

Urdu:

  • اسپینل

Further Reading / External Links