Sunstone

Sunstone is a gorgeous gemstone which appears to shine with light from certain angles, due to reflections caused by copper inclusions.

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Appearance, Uses and History

A few important distinctions need to be made regarding Sunstone.

Sunstone is a Plagioclase Feldspar, and plagioclase is a group of Feldspar minerals which consist of varying degrees of Albite and Anorthite. Members of the plagioclase group include Albite, Oligoclase, Andesine, Labradorite, Bytownite and Anorthite.

In many cases, members are referred to as plagioclase rather than a specific members name, because it can be extremely difficult to tell these minerals apart without lab tests. Some websites online will refer to Oregon Sunstone as plagioclase feldspar, others will refer to Oregon sunstone as a copper bearing Labradorite – both are correct.

Now that’s been ‘cleared up’; Sunstone demonstrates a glittering spangled optical effect similar to aventurescence. This optical effect is known as schiller, and is the main reason Sunstone is prized for jewellery. Oregon Sunstone is particularly prized due to larger inclusions of native copper, which are sometimes rainbow coloured and referred to as ‘lattices’ – with the name ‘rainbow lattice Sunstone’ given to the best pieces.

Sunstone, as far as I can tell, is used exclusively as a decorative stone – for jewellery making, or polished, or tumbled, or sold as mineral specimens.


Locales

Sunstone is found in Australia, Canada, India, Norway, Russia, Tanzania, and the USA. Oregon sunstone is by far the most prized.


Mineralogy

Chemistry
Sunstone is a form of plagioclase Feldspar with the chemical formula (Ca,Na)((Al,Si)2Si2O8)
Colours and Variations
Red, green, yellow and peach body colour with varying colours of iridescence.
Streak
Luster
Vitreous
Fracture
Conchoidal, uneven, splintery
Transparency
Transparent.
Crystal habit
Euhedral crystals, granular, massive
Mohs hardness
6.0 – 6.5
Specific Gravity
2.62 – 2.67
Fluorescence
N/A
Easiest testing method
Visual examination, reddish or golden plates inside.
Common Treatments
None.

Photos of Sunstone

Oligoclase-Sunstone from India2
Oligoklas-norway hg
NT41

Anorthoclase feldspar with iridescent hematite inclusions (Potanikha Quarry, Kasli, Ural Mountains, Russia) 7 (29810807540)
Rainbow Lattice Sunstone rough
Heliolite

Labradoriteoregonsunstone
Aventurinfeldspat

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:

  • حجر الشمس

Hindi:

Portuguese:

  • pedra do sol

Bengali:

Indonesian:

  • batu matahari

Punjabi:

English:

  • sunstone

Italian:

Russian:

  • солнечный камень

French:

  • pierre de soleil

Japanese:

  • サンストーン

Spanish:

  • piedra solar

German:

  • Sonnenstein

Korean:

  • 선 스톤

Thai:

Gujurati:

Mandarin and Traditional Chinese:

  • 日长石
  • 太阳石
  • 太陽石

Urdu:

  • سورج پتھر

Further Reading / External Links