LABRADOR FELDSPAR :

Synonym of labradorite

LABRADOR HORNBLENDE :

Synonym of hyperstene

LABRADORITE :

Etym. Named after the region of Labrador in Canada
Stone belonging to the big family of the feldspars  more precisely of the series of the plagioclases  containing 50 to 70% of Ca and 50 to 30 % of Na
(NaAlSi₃O₈)(CaAl₂Si₂O₈)

Physical and optical properties

-          Colours : ash-grey with iridescence and chatoyant reflections of blue, green, golden, or brown-red tints
-          Transparency : transparent to opaque
-          Lustre : vitreous
-          Hardness : 6 to 6.5
-          Density : 2.60 to 2.76
-          R.I. : 1.559 – 1.568 (opaque)
              1.560 – 1.570 (transparent)
-     biaxial positive
-          Birefringence : 0.009 to 0.011
-          Dispersion : 0.010
-          Cleavage : perfect
-          System triclinic

LABRADORITE of MADAGASCAR :

Variety of colourless to grey labradorite with dark blue iridescence, having an aspect intermediate between a moonstone and a labradorite

LABRADORITE-MOONSTONE :

See labradorite of Madagascar 

LABRADOR-MONDSTEIN :

German Name for labradorite-moonstone

LACROISITE :

Mixture of Rhodocrosite and Rhodonite 

LADJWARD-JUI :

Afghan Name for Lapis-Lazuli

LAKE GEORGE DIAMOND :

Prohibited Appellation for a bi-pyramidal (bi-terminated) rock crystal of Herkimer County, New-York

LAKE SUPERI0R AGATE :

Prohibited Appellation for a thomsonite  with the same provenance than the nicely banded agates; or appellation for these agates from Lake Superior

LAKE SUPERIOR FIRE AGATE :

Prohibited Appellation for an imitation of opal , made out of glass

LAKE SUPERIOR GREENSTONE :

Prohibited Appellation for a chlorastrolite 

LANDERITE :

Variety of pink grossular garnet  of Xalostoc, Morelos, Mexico

LAO KAN C’HING JADE :

Chinese Term designating a bluish jade

LAO KAN HUAN JADE :

Chinese Term for a deep yellowish jade

LAPIS :

Etym. : from the Latin word : stone
Name employed for designating generally lapis lazuli  

(GERMAN) LAPIS :

Prohibited Appellation ; it is a light grey jasper from Nunkirchen in Germany ; tinted blue to imitate lapis lazuli

(ARDENS) LAPIS :

Latin name designating amber .

(CALIFORNIAN) LAPIS :

Prohibited Appellation for a dumortierite-quartz

(CHILIAN) LAPIS or LAPIS from CHILE :

Variety of lapis lazuli of blue colour more pale than the lapis lazuli from Afghanistan and strongly  veined with matrix of calcite white

(COPPER) LAPIS :

Prohibited Appellation for azurite  

(ITALIAN) LAPIS :

Designates the German Lapis or Swiss Lapis = chalcedony or jasper, tinted blue, Prohibited Appellation

LAPIS LAZULI :

Etym. From the Latin : lapis = stone , and the Arabic word azul = heaven.
3NaAlSiO₄.NaS₃
It is an aggregate of several minerals, among them : the most important is blue lazurite ( also called ‘bleu d’outremer’ in French), containing small inclusions of pyrite

Physical and optical properties :

Colours : blue, ‘blue outremer’ to blue violet
Transparency : opaque
Hardness : 5 to 6
Density : 2.35 to 2.95 (generally 2.38 to 2.42)
R.I. : 1.50 to 1.51
System : cubic (lazurite)

LAPIS MUTABILIS :

Prohibited Appellation for a hydrophane opal  

LARDITE :

Synonym of agalmatolite 

LASULITE :

Synonym of lazulite 

LASURAPATITE :

German Term. Variety of blue apatite

LASURFELDSPATH :

German Term. Variety of orthose and having the blue outremer colour, from Siberia

LASURITE :

Synonym for lazurite 

( for Haidinger : Synonym for azurite)

LASURQUARTZ :

German name for blue quartz

LASURSTEIN :

German name for lazurite 

LAVENDINE :

Synonym of amethyst quartz

LAWROFFITE :

Variety of vanadiferous diopside

LAWSONITE :

H₄CaAl₂.SiO₁₂
Physical and optical properties :

-           Colours : colourless to pale blue
-          Hardness : 8
-          Density : 3.08 to 3.09
-          R.I. : 1.665 – 1.684
-          Biaxial positive
-          Birefringence : 0.019
-          System orthorhombic

LAZULI LITHIQUE :

French term. Synonym of lithoxyle

LAZULITE :

Or lasulith or klaprotine
(Fe, Mg)Al₂(OH ;PO₄)₂

Physical and optical properties :

Colours : light blue, sky blue, sometimes resembling to the blue of lazurite
Transparency : transparent to opaque
Hardness : 5 to 6
Density : 3.06 to 3.12
R.I. : 1.603 – 1.640 (+0.003)
Birefringence : 0.031 to 0.034
Biaxial negative
System monoclinic

LAZULITH :

Synonym of lazulite
( according to Schlotheim : Synonym of cordierite )

LAZURITE :

Principal component of lapis lazuli
( not to be confounded with azurite that is a carbonate, or lazulite that is a phosphate) 3NaAlSiO₄Na₂S

Physical and optical properties :

Colours : blue, greenish blue to blue-violet, Prussian blue
Transparency : opaque
Hardness : 5 to 5.5
Density : 2.38 – 2.75
R.I. : ± 1.500
System cubic

LEBERKIES :

German name for marcassite

LEBERSTEIN :

German name for pyrite

LECHLEITNER SYNTHETIC EMERALD :

Synthetic emerald fabricated by Lechleitner. Synonym for emerita 

LECHOSOS OPAL :

English Name.
Opal showing a mainly deep green play of colour (Kraus & Holden )
Fire opal from Mexico with a play of colour emerald green and carmine or blue-violet ( Bauer -Spencer -Schlossmacher )
Fire opal from Mexico presenting simultaneously the play of colour from opal and its own red body-colour ( Schlossmacher )

Mexican colourless and transparent opal having a play of colours deep emerald green and / or dark blue, dark violet, pink, carmine and purple ( Eppler )

LEDERITE :

Variety of sphene 

LEELITE :

Synonym of orthoclase 

LEMANITA :

Spanish name for jade

LENBOUK :

Burmese name serving to designate a ruby of first quality of more then 4.00 ct

LENNILITE :

Green variety of ortbose

LEONITE :

Commercial Name for a (French term) " pierre du Tibet "  , of yellow colour

LEOPARDITE :

Variety of amazonite

LEPIDOLITE :

Lithic Mica of pale reddish violet colour; matrix of tourmaline

LEPIDOMELANE :

Ferriferous Mica 

LEUCITE :

Equally called falsely white garnet or white schorl or vesuvianite garnet .

KAlSi₂0₆

Physical and optical properties :

Colours : colourless, white to grey

Transparency : transparent to translucent

Lustre : vitreous

Hardness : 5.5 to 6

Density : 2.45 to 2.50

R.I. : 1.508 – 1.509 (±0.001)

Dispersion : 0.008

Uniaxial positive

System tetragonal (crystallises under pseudo-cubic form)

LEUCO-GARNET :

Variety of colourless grossular garnet .

LEUCO-SAPHIR :

French name for leuco-sapphire.

LEUCO-SAPPHIRE :
Colourless and transparent natural white sapphire, not to be confounded with the Prohibited Appellation " white sapphire " for a synthetic colourless stone .

LEUCOXENE :

Synonym of sphene  ( for others anatase )

LEUKORITE :

Synonym for bakelite

LEUKOSAPHIR :

German name for leuco-sapphire