LIDDICOATITE :
Variety of lithium tourmaline.
Ca(Li₂Al)Al₆(Si₆O₁₈)(BO₃)₃(OH)₃F
Etym. : named in honour of M. Liddicoat, American gemmologist, pioneer of  modern gemmology.
See also :
Liddicoatite Tourmaline From Anjanabonoina, Madagascar. (Gems & Gemology, Spring 2002)

LIGURITE :
Variety of sphene of apple green colour

LILALITE :
Synonym of lepidolite

LIMBILITE :
Variety of pink peridot or alteration of peridot ( mixture of peridot and of limonite) or vitreous paste of Limburgite.

LIMBITE :
Synonym of Limibilite

LIME JADE :
Term employed by the Chinese for designating a jade of warm green colour

LIMONITE :
Oxide of brown iron encountered as inclusions in gemstones, or as matrix-material in turquoises (S.G. 3.8)

LINDIA SYNTHETIC EMERALD :
English commercial Name for a synthetic emerald, fabricated in the USA by the Linde Air Products Co.

LINDIA SYNTHETIC RUBY :
English commercial Name for a synthetic ruby fabricated in the U.S.A. by the Linde Air Products Co.

LINDIA SYNTHETIC SAPPHIRE :
English commercial Name for a synthetic sapphire fabricated in the U.S.A. by the Linde Air Products Co .

LINTONITE :
Variety of thomsonite ressembling agate  with des alternated bands of greens and pinks

LION’S EYE :
Name given in certain regions to a Quartz cat’s eye.

LIPARITE :
De Glockner : Synonym of fluorite
De Casoria : Synonym of Chrysocolle

LIROCONITE :
Hydrated Arsenate of Al and of Cu
Cu₂Al(As,P)O₄(OH)₄.4H₂O
Physical and optical properties :
Colours : blue to green
Lustre : vitreous
Hardness : 2 to 2.5
Density : 2.9 to 3
R.I. : 1.610 – 1.670
System monoclinic

LITHIONAMETHYST :
German Synonym for kunzite  ; Prohibited Appellation

LITHIONSMARAGD :
Prohibited Appellation German for hiddenite

LITHOXYDE or lythoxyl or lithoxylithe :
Opalised wood of which the original structure of wood is visible

LITHOXYLON :
Synonym for wood opal

LIVER OPAL :
English Synonym for a menilite

LIZARDITE :
Variety of serpentine
Green blackish with traces of reds, reddish spotted green, dark green spotted light green

LLANCA :
Synonym for chrysocolle 

LOBOÏTE :
Variety of magnesium containing idocrase

LONSDALEÏTE :
Diamond with a hexagonal crystalline structure obtained on heating crystallised graphite to 7.000 °C and more with 200.000 kg/cm² of pressure
Hardness 10
One has found some material in meteorites

LOS CERRILL0S TURQUOISE :
Turquoise from the mines of Los Cerrillos ( near Mt. Chalcechiite ) and producing the American turquoises of the best quality. At present these mines are exhausted

It’s a mixture of apophyllite and of quartz.

LOVE’S ARROWS :
English name for  flèches d’Amour .

LOVE STONE :
English Synonym for aventurine quartz .

LOXOCLASE :
Orthose feldspar with albite

LUCHSSAPHIR :
German name for cordierite

LUCINITE :
Variety of variscite from Lucin (Utah)

LUCITE :
Commercial name for a transparent plastic ( product of the firm Du Pont )
R.I. : 1.49
S.G. : 1.I9

LUCKY STONE :
English name for staurolite

LU JADE :
Chinese Name (Lu YU) for a green bluish jade

LUNAIRE :
Synonym of moonstone 

LUNARIS :
Latin name for moonstone 

LUNAR STONE :
English name given to a variety of phosphorescent barytine 

LUSSATITE :
Variety of chalcedony .

LUTECINE :
Variety of quartz

LUTHOS LAZULI :
Prohibited Appellation for a violet fluorite  

(LUX) SAPPHIRE :

Prohibited Appellation for a cordierite .

LYBIAN GLASS :

A natural glass discovered for the first time in 1932 in the Lybian desert. Already used in Neolithic times for making tools.

It is a meteorite impact glass; little different in composition from tektites.

Composed of 98 % of silica much more than moldavite or obsidian .

- colour : pale yellowish green

- Hardness : 6

- S.G. : 2.2

- R.I. : 1.46 (source : Smith ; Shipley)

- slightly opalescent (source : Anderson)

LYCHNIS :
Ancient Appe11ation for a spinel  of ruby colour

LYDIAN STONE or LYDITE :
English name for Lydian Quartz . See basanite . Variety of black jasper, named " touch stone " (French : Pierre de touche)

LYDITE :
Synonym of Lydian Quartz .

LYDIENNE :
A French synonym for Lydian Quartz .

LYMBILITE :
Variety of pink peridot

LYNCURION :
Synonym of zircon according to Theophrastus

LYNCURIUM :
Synonym of Lynx Stone  or of amber (according to Plinius) ; for others Synonym of tourmaline

LYNX EYE :
English Name for oeil de lynx  (French)

Name given to a mainly green labradorite

LYNX SAPPHIRE :

Prohibited Appellation for a dark blue cordierite  .
Term equally employed for designating a dark blue sapphire from Sri Lanka ( Smith) or a very pale blue sapphire with girasol effect ( Schlossmacher )

LYNX STONE :
English Name for lyncurium