JACINTA GARNET :
Commercial English Term serving to designate a yellowish garnet.

JACINTHE :
Other orthograph for Hyacinth.

JACKSONITE :
Variety of Prehnite ; designates equally a variety of Chrysocolla.

JACOBSITE :
Spinel containing Fe, Mn and Mg.

JACUMBA HESSONITE :
Commercial name for a hessonite from Jacumba Hot Springs, San Diego, California.

JACUT :
Arab (old Arab, Persian, etc.) language. Synonym for a Corundum and more specifically for a Sapphire.

JADE :
Jade is a name comprising two types of mineralogical distinct species :  nephrite and jadeite.

(AFRICAN) JADE :
Prohibited Appellation for a green grossular garnet, called equally " Transvaal Jade ".

(AMAZONE) JADE :
Prohibited Appellation for Amazonite .

(AMERICAN) JADE :
Equally called " Wyoming jade ".
Nephrite from Wyoming, U.S.A..
Equally Prohibited Appellation for a Californite .

(ANTILOPE) JADE :
Chinese term designating a certain variety of Jade.

(AUSTRALIAN) JADE :
Prohibited Appellation for Variscite.

(BOWENITE) JADE :
Prohibited Appellation for a Bowenite.

(BURMESE) JADE :
Finest known jadeite. From mines in Mogaung, subdivision of Myitkyina district in Upper Burma.

Burma jade is the term used in the Orient to distinguish it from any and all varieties of Nephrite.

(CALIFORNIAN) JADE :
Prohibited Appellation for a Vesuvianite or Californite.

(CANTON) JADE :
Name either for la nephrite, or for a jadeite handled in Canton, China.

(CHINESE) JADE:
Ou Jade for Chine.
Synonym for Jadeite.
Equally a Prohibited Appellation for a serpentine.

(CHI KU PAI) JADE:
Appellation given par the Chinese to heat-treated jade to modify its colour.

(COLORADO) JADE :
Prohibited Appellation for Amazonite.

(KOREA) JADE or KOREAN JADE :

Prohibited Appellation for a serpentine  (the bowenite variety ) ;

term equally used for designating an agalmatolite  artificially tinted

or an imitation in glass having the green colour of jade ;

May equally designate an impure variety of jade (nephrite-jade)

(EMERALD) JADE :
Prohibited Appellation Synonym for Imperial Jade.

(IMPERIAL) JADE :
Name given to an apple green or emerald green jadeite.

(MEXICAN IMPERIAL) JADE :
Prohibited Appellation for a variety of Mexican Calcite coloured artificially green.

(NEW ZEALAND) JADE :
Synonym for nephrite.

(OREGON) JADE :
Prohibited Appellation for a variety of green quartz (plasma) found in the U.S.A.

(SWISS) JADE :
Prohibited Appellation for a jade turned green after treatment.

(YUNNAN) JADE :
Variety of dark green jade from China.

JADE-ALBITE or JADEITE-ALBITE :

Mixture of albite feldspar and jadeite from Upper-Burma .
Na(Al,Cr,Fe)(SiO₃)₂ 
Physical and optical properties:
Colours : strong green to greyish green, brownish green with black spots.
Hardness : 6.
S.G. : 2.77.
R.I. : average 1.525 to 1.540.

JADE CAMPHRE :
French term. Translucent whitish jade.

JADE DES INDES :
Or jade indien. French term.
Prohibited Appellation for a green aventurine quartz.

JADEITE or JADE-JADEITE :
Jade-jadeite is formed of short and blocky prisms of inter-twined jadeite.
Jadeite is a pyroxene, silicate of aluminium and sodium .
NaAl(Si₂0₆)
Imperial jade is characterised by the presence of chrome coupled to a weak concentration of iron, which gives it this emerald colour. The spectrum for chrome may than be sometimes visible.
Physical and optical properties:
-  Colours : white (when pure), pink, lavander to violet, yellow, brown, different hues of green, blackish . Here also, the presence of iron darkens the mineral (sometimes called chloromelanite).
- Transparency : translucent to opaque
- Hardness : 6.5 to 7
- R.I. : 1.654 –1.667; average (spot method) : 1.66
- Birefringence :  +0.013 , often none
- S.G. : 3.3
- Fracture : uneven
- System : monoclinic
Occurrences :
Metamorphic Rocks.
Jadeite : Jade mountain in Khotan, Andes, Burma, China.
Nephrite : Siberia, Taiwan, USA, Canada, New Zealand.
Treatments :
- to give it an (ancient looking ) satin aspect : a heat-treatment is applied to jades.
- a colouring treatment is equally applied to jades that are to light or yellowish in colour. Only with sophisticated analysis with spectrophotometers, etc in visible and infra-red permits to detect these treatments by tincture
- treatment by filling with among others, plastic materials to give the stones more lustre and translucency; again sophisticated apparatus is necessary for detection
- the cleaning with acids of jades presenting reddish or yellowish traces allows these gems to recuperate their initial sought after colour ; afterwards the fractures are also filled with plastic material.
Confusions :
Massif grossular, massif vesuvianite, massif zoisite, smithsonite, phrenite with a vitreous lustre,  massif apatite, fractured emerald, massif micas (verdite), aventurine quartz, fluorite, serpentine,…
Imitations :
Glass, plastic, different tinted rocks (marbles, quartzites, …) + doublets.
Synthetics :
Their exists a synthetic of Russian or American fabrication .

(AFRICAN) JADEITE :
Prohibited Appellation for Verdite.

JADEOLITE :
A chromiferous syenite of deep green colour resembling a jade and more particularly Jadeite from the mines of Bhamo in Burma.

JADE de SAUSSURE :
French term. Prohibited Appellation for saussurite.

JADE STYRIEN :
Or jade de Styrie.
French term.
Prohibited Appellation for a variety of aluminium containing serpentine that is used as an ornamental stone (pseudomorphite).

JADE TENACE :
French term. Prohibited Appellation for saussurite.

JAIS :
French for jet.

JALITE :
Synonym for Hyalite.

JAMESONITE :
Lead iron antimony sulfide.
Etym. : named after mineralogist Robert Jameson (1774-1854)
Pb₄FeSb₆S₁₄
Jamesonite is also wrongly used as synonym for chiastolite.

JARGON :
Old term used by some to designate a zircon of cinabar or vermillion colour.
But mainly an old term used to designate a colourless zircon (these stones used as imitations for diamond in the 19^th century).

JARGOON :
Synonym for Jargon.

JASPAGATE :
Mixture of jasper and chalcedony or agate, with predominantly chalcedony. 

JASPE FLEURI :
French term. Variety of jasper agate with many colours.

JASPER :
Siliceous rock.
SiO₂
This massive opaque fine grained rock contains for up to 80% or more micro-crystalline quartz.
Physical and optical properties:
Colours : all colours and mixed colours, also spotted and striped.
Transparency : opaque
Hardness : 6.5
R.I. : about 1.54
S.G. : 2.6 to 2.9
Occurrences :
Deposits are found all over the world : Ural, India, Bohemia, Sicily, Germany, U.S.A., Africa, etc.

(BANDED) JASPER :
Variety of jasper with different colours disposed en bands.

(BIRD’S EYE) JASPER :
Name given par the Americans to a variety of jasper containing spherules of colour.

(BLACK) JASPER :
Or Lydian jasper, or Lydian quartz.
Black jasper used as a touch stone .

(BOLIVIAN) JASPER :
Variety of red jasper from Bolivia.

(EGYPTIAN) JASPER :
Variety of jasper.
Synonym for silex from the Nile (or in German : Nilkiesel).

(ELEPHANT) JASPER :
Variety of jasper light brown to dark brown colour, containing a mass of small black inclusions of dendrites.

(GREEN) JASPER :
Synonym for heliotrope, for prase, or for plasma.

(OPAL) JASPER :
Variety of common opal, generally containing a lot of iron very of yellow-brown, brown-red to red  colour and having the appearance of jasper.

(ORBICULAR) JASPER :
Variety of jasper containing spherules of different colours , mainly yellow green and brown and with different nuances from light to dark.

(SWISS) JASPER :
Variety of vivid red jasper rouge, having small portions of clear quartz.

JASPERH :
12th stone of the Rational of the High Priest of the Jews in antiquity, represented by the jasper.

JASPER JADE :
Name used by the Chinese to designate products that imitate jade, like serpentine, quartz o a mixture of quartz and jade.

JASPERRINE :
Variety of jasper with bands of different colours.

JASPERROIDES :
Secondary formation of hydrothermal veins giving birth to very coloured jasper (silicified clay).

JASPE SANGUIN :
French for blood jasper.  See heliotrope.

JASPILITE :
Term used in the region of Lake Superior to designate a brilliant red jasper with black bands of hematite.

JASPONYX :
Opaque onyx resembling jasper.

JAYET :
Synonym for jet.

JEAT :
Synonym for jet.

JELLETITE :
Variety of melanite (andradite).

JENZSCHITE :
Variety of opal.

JEREMEJEVITE :
Borate of aluminium and f beryllium.
Mineral very rare forming small hexagonal colourless crystals.
Al₆B₅O₁₅(F,OH)₃ 
Physical and optical properties:
- Colours : colourless to bluish.
- Transparency : transparent
- Hardness : 6.5 to 7
- R.I. : 1.640 - 1.653 (birefr. : 0.013)
- Uniaxial negative
- S.G. : 3.28
- system : hexagonal
Occurrences :
Germany, Russia, Namibia ( pegmatite, associated to orthose).

JERNGLANS :
Synonym for hematite.

JET :
A material of organic origin, a bituminous coal.
The texture is compact ; the structure of wood is but rarely visible.
Physical and optical properties:
- Colours : black, dark brown
- Transparency : opaque
- Lustre : velvety
- Hardness : 2.5 to 4
- R.I. : 1.64 to 1.68
- S.G. : 1.10 to 1.40
 - Fracture : conchoidal.
- Sometimes, slight static electricity.
Occurences :
At Whitby (Great Britain)), Spain, France, Germany, Poland, Russia, U.S.A.
Treatments :
Plastified jet (to make it more hard and solid) has been found.
Confusions :
- The most convincing ones are carbonised rocks.
- Bituminous schists (more compact than jet).
- Albertite, a natural asphalt of black colour with low density (1.10) and soft (2.5).
- Lignites of low density (1.2) and equally tender (2.5).
- Cannel coal, more compact, more fragile , black and dull lustre.
- Anthracite from Pennsylvania : very brilliant, waxy to semi-metallic lustre and quite dense (1.5 to 1.7).
- Onyx.
Imitations :
- black glass (" Jet from Paris " Prohibited Appellation).
- tinted horn and tinted mother-of-pearl.
- vulcanised rubber.
- plastics : celluloid, bakelite, polystyrenes

JET STONE :
Variety of black tourmaline (Source : Power).

JEVREINOVITE :
Variety of idocrase.

JEWREINOWITE :
Variety of idocrase.

JOALAM :
Considered to have been in antiquity the 6th stone of the Rational of the High Priest of the Jews, represented by the diamond.

JOAQUINITE :
Titano-silicate of honey colour .
Ba₂NaCe₂Fe(Ti, Nb)₂Si₈O₂₆(OH,F).H₂O

JOB'S TEARS :
Local name serving to designate a peridot from Arizona and New Mexico.

JOCHROIT :
Original orthograph for iochroite.

JOHNITE :
Synonym for oriental turquoise or for vitreous turquoise.

JOHNSTONOLITE :
Variety of garnet containing Mn

JOHNSTONOTITE :
Variety of andradite garnet.

JOLITH :
Synonym for Cordierite.

JOURADO DiAMOND :
Prohibited Appellation for a colourless imitation stone.

JUAN JADE :
Mixture of white and rouge jade.

JURINITE :
Synonym for brookite.