LABRADORITE Polished Natural Iridescent Gemstone Mineral Crystal Specimen for Sale

On eBay Now...

LABRADORITE Polished Natural Iridescent Gemstone Mineral Crystal Specimen For Sale

When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

LABRADORITE Polished Natural Iridescent Gemstone Mineral Crystal Specimen:
$39.99

This specimen weighs 38.88grams. It measures 62 mm x 30 mm x 17 mm.
I offer a shipping discount for customers who combine their payments for multiple purchases into one payment!
The discount is regular shipping price for the first item and just 50 cents for each additional item!
To be sure you get your shipping discount just make sure all the items you want to purchase are in your cart.
sales you win are added to your cart automatically.
For any \"buy it now\" items or second chance offers, be sure to click the \"add to cart\" button, NOT the \"buy it now\" button.
Once all of your items are in your cart just pay for them from your cart and the combined shipping discount should be applied automatically.I offer a money back guarantee on every item I sell.
If you are not 100% happy with your purchase just send me a message to let me know
and I will buy back the item for your full purchase price.
Hi there. I am selling this beautiful labradorite carved sphere! The labradorite is from Brazil and it was also hand carved in Brazil. If you have any questions do not hesitate to ask me. Thanks so much for visiting my store and have a great history
ToolsFrom Wikipedia, the free encyclopediaLabradorite
Labradorite in a polished rock slabGeneralCategory Adularescence, tectosilicateFormula(repeating unit) (Ca,Na)(Al,Si)4O8, where Na is 30-50% & Ca is 50–70%Crystal system TriclinicCrystal class Pinacoidal (1)(same H-M symbol)Unit cell a = 8.155 Å, b = 12.84 Åc = 10.16 Å; α = 93.5°β = 116.25°, γ = 89.133°; Z = 6IdentificationColor Gray, gray-white, brown, greenish, pale green, blue, orange, pink, yellow, colorlessCrystal habit Crystals typically thin and tabular, rhombic in cross section, striated; massiveTwinning Common by albite, pericline, Carlsbad, Baveno, or Manebach twin lawsCleavage Perfect on {001}, less perfect on {010}, intersecting at near 90°; distinct on {110}Fracture Uneven to conchoidalMohs scale hardness 6–6.5Luster Vitreous to pearly on cleavagesStreak WhiteDiaphaneity Translucent to transparentSpecific gravity 2.68 to 2.72Optical properties Biaxial (+)Refractive index nα = 1.554–1.563nβ = 1.559–1.568nγ = 1.562–1.573Birefringence δ = 0.008–0.0102V angle Measured: 85°Dispersion NoneOther characteristics Labradorescence (iridescence, schiller optical effect)References [1][2][3]Labradorite ((Ca, Na)(Al, Si)4O8) is a calcium-enriched feldspar mineral first identified in Labrador, Canada, which can display an iridescent effect (schiller).
Labradorite is an intermediate to calcic member of the plagioclase series. It has an anorthite percentage (%An) of between 50 and 70. The specific gravity ranges from 2.68 to 2.72. The streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573 and twinning is common. As with all plagioclase members, the crystal system is triclinic, and three directions of cleavage are present, two of which are nearly at right angles and are more obvious, being of good to perfect quality (while the third direction is poor). It occurs as clear, white to gray, blocky to lath shaped grains in common mafic igneous rocks such as basalt and gabbro, as well as in anorthosites.
OccurrenceThe geological type area for labradorite is Paul\'s Island near the town of Nain in Labrador, Canada. It has also been reported in Poland, Norway, Finland and various other locations worldwide, with notable distribution in Madagascar, China, Australia, Slovakia and the United States.[2]
Labradorite occurs in mafic igneous rocks and is the feldspar variety most common in basalt and gabbro. The uncommon anorthosite bodies are composed almost entirely of labradorite.[4] It also is found in metamorphic amphibolites and as a detrital component of some sediments. Common mineral associates in igneous rocks include olivine, pyroxenes, amphiboles and magnetite.[1]
LabradorescenceSee also: adularescence
Labradorescence in labradoriteDuration: 5 seconds.0:05Video of labradorescence in labradorite, visible as the angle of view changesLabradorite can display an iridescent optical effect (or schiller) known as labradorescence. The term labradorescence was coined by Ove Balthasar Bøggild, who defined it (labradorization) as follows:[5]
Labradorization is the peculiar reflection of the light from submicroscopical planes orientated in one direction (rarely in two directions); these planes have never such a position that they can be expressed by simple indices, and they are not directly visible under the microscope.
Contributions to the understanding of the origin and cause of the effect were made by Robert Strutt, 4th Baron Rayleigh (1923), and by Bøggild (1924).[5][6][7]
The cause of this optical phenomenon is phase exsolution lamellar structure,[8] occurring in the Bøggild miscibility gap.[9] The effect is visible when the lamellar separation is between 128 and 252 nm (5.0×10−6 and 9.9×10−6 in); the lamellae are not necessarily parallel;[9] and the lamellar structure is found to lack long range order.[10]
The lamellar separation only occurs in plagioclases of a certain composition; those of calcic labradorite (50–70% anorthite) and bytownite (formula: (Ca0.7-0.9,Na0.3-0.1)[Al(Al,Si)Si2O8], i.e., with an anorthite content of ~70 to 90%) particularly exemplify this.[8][11] Another requirement for the lamellar separation is a very slow cooling of the rock containing the plagioclase. Slow cooling is required to allow the Ca, Na, Si, and Al ions to diffuse through the plagioclase and produce the lamellar separation. Therefore, not all labradorites exhibit labradorescence (they might not have the correct composition, cooled too quickly, or both), and not all plagioclases that exhibit labradorescence are labradorites (they may be bytownite).
Some gemstone varieties of labradorite exhibiting a high degree of labradorescence are called spectrolite.