SFENO :

Synonym for sphene .

SHATTUCKITE :

Etym. : after Shattuck in Arizona

Aggregate

Cu₆[(OH)₂ú (SiO₃)₄]

Physical and optical properties :

Colour : deep blue with green and white

Transparency : transparent to translucent

Hardness : 3.5 to 4

Density : 3.8

R.I. : 1.752 – 1.815

Birefringence : 0.063

Biaxial positive

System : monoclinic

SHEPARDITE :

Synonym for enstatite .

SHERRY TOPAZ :

- English name given to a topaz having the colour sherry.

- Prohibited appellation for a citrine of the same colour .

SHIMMERMALACHITE ( or SCHIMMERMALACHITE )

Malachite from California ; silky and with a slightly chatoyant effect.

SHWELU :

Indian Name for a pale green jadeite with spots and lines .

SIAMESE AQUAMARINE :

Prohibited appellation for a blue zircon, or a greenish spinel .

SIBERIAN RUBY :

Prohibited Appellation for a red tourmaline .

SIBERITE :

Variety of tourmaline from Siberia ; red to violet for some; black to violet for others .

SICILIANITE :

Synonym for Celestine .

SIDERITE :

FeCO₃

Physical and optical properties :

Colour : brown, yellow

Transparency : transparent to opaque

Hardness : 4 to 4.5

Density : (±)3.89

R.I. : 1.633 – 1.875

Birefringence : 0.242

Uniaxial negative

System : trigonal

SIDEROMELANE :

Synonym for obsidian .

SIEGSTEIN :

German Name given in the old days in Germany to a star sapphire.

SILEX :

Variety of jasper, or very compact chalcedony

Colour : grey, brown, yellow, black

Density : 2.59 to 2.61

(MANGANESE) SILEX :

Old and Prohibited Appellation for a rhodonite .

SILEX from the NILE :

Name given to a jasper from Egypt .

SILEX XYLOIDE :

Name wrongly given to a jasper .

SILICA GLASS :

English name given to a natural glass, more riche in silicon dioxide than obsidian or moldavite discovered in the Libyan desert

Colour : pale yellowish green to yellow, with a slight opalescent effect

Hardness : 6

Density : 2.2

R.I. : 1.46

SILICEDUS MALACHITE :

English Name for a chrysocolla .

SILICIFIED WOOD :                                                                                                            Synonyms : fossilized or petrified wood. The (organic) wood has not actually changed into stone but the wood has disappeared with time and the space left has been filled with chalcedony

(agate ), jasper or (much less frequent) opal; Thanks to the continuous afflux of silica molecules replacing in time the molecules of wood. This mutation is caused by the contact of the wood with water charged with silica. So its composition is silicon dioxide.
The particular colours of the fossilized wood that appear sometimes are caused by the presence of argiles.
The physical and optical characteristics of silicified wood are identical to those of chalcedony and agate with the initial texture of the wood staying visible, sometimes with the loupe.
Occurrence :
U.S.A. (Arizona), Madagascar, Canada, …
Inclusions:
White silicified worms are present in certain silicified woods from Australia .

SILICI0PHITE :

It is an obsidian like mixture of opal and serpentine .

SILICITE :

Variety of labradorite .

SILLIMANITE :

Etym. : named after the mineralogist Dr. Benjamin Silliman ( 1779- 1864 ), U.S.A.

Synonym : Fibrolite

Al₂SiO₅

Physical and optical properties :

Colour : blue-violet to grey yellowish

Transparency : transparent to opaque

Lustre : vitreous

Hardness : 6 to 7.5

Density : 3.24 (±0.02)

R.I. : 1.659 (+0.002 –0.004) – 1.680 (+0.004 –0.001)

Birefringence : 0.009 to 0.012

Trichroisme : strong, medium, weak

System : orthorhombic

SILVER PEAK JADE :

Prohibited Appellation, local name given to malachite in Nevada .

SILVER STONE :

English Name for a moonstone .

SILVER TOPAZ :

Name given in South Africa (Cape province) to designate a white topaz .

SIMAVOPAL :

English Name given to an opal coming from N.E. of Smyrna in Turkey .

Colour : colourless, milky white, brownish ; equally yellow, orange ( red, resembling fire opal ).

SIMETITE :

Name for amber from Sicily; red to orange, light yellowish to brown .

SIMON STONE :

Name English given to an opal from Turkey, See "Simavopal".

SINHALITE :

Etym. from Sinhala ; Sanskrit Name for Sri Lanka .

This mineral has long been classified with the peridot, now considered as a mineral in its own right; one can make the distinction from peridot by a large supplementary absorption band in its spectrum at 463 nm.

MgAlBO₄   

Physical and optical properties :

Colour : pale yellow-brown to golden yellow, brown, greenish-brown, green with yello-golden

            tinge, black

Transparency : transparent to translucent

Lustre : vitreous

Hardness : 6 to 7

Density : 3.46 to 3.50

R.I. : 1.668 (+0.008 –0.003) – 1.707 (+0.005 –0.003)

Birefringence : 0.036 to 0.042

Biaxial negative

Trichroism : distinct : green, pale brown, dark brown

System : orthorhombic

SINOPAL :

Variety of aventurescent quartz with red mineral inclusions of iron .

SINOPLE :

Variety of hematoïde-quartz; synonym for sinopal .

SIOUX FALLS JASPERR :

Decoratif brown Jasper .

SKAPTOLITE :

Synonym for scapolite .

SMALTITE or SMALTINE :

(Co,Ni)As₃

Colour : white to grey

Transparency : opaque

Lustre metallic

Hardness : 5.5 to 6

Density : 6.1 to 6.9

System : cubic

SMARAGD :

German Name for emerald .

SMARAGDFLUSS :

German  Prohibited Appellation for a fluorite .

SMARAGD-MALACHIT :

German Prohibited Appellation for a dioptase .

SMARAGD-MUTTER :

German Prohibited Appellation for smaragdite or prase .

SMARAGDOLIN :

Commercial name for a glass with beryl of Viennese fabrication, serving to imitate emerald

Hardness : 5 to 5.5

Density : 3.3 to 3.45

R.I. : 1.62

SMARAGDUS :

Latin Name for emerald, but serving equally to designate other green stones in those days .

SMARAGTITE :

Variety of emerald green amphibole, or resembling a jade ;

or a hornblende close to diopside, used also to imitate jade .

SMARYL ou SMARYLL :

Doublet composed of 2 parts of Beryl and imitating emerald. There existe also some that are composed of Beryl and tourmaline .

SMEGMATITE :

Synonym for saponite .

SMERALDO :

Synonym for emerald .

SMITHSONITE :

Etym. after James Smithson ( 1750-1829 ) founder the Smithsonian Institute in Washington ; synonym for zinc-spar or calamine .

ZnC0₃ 

Physical and optical properties :

Colour : whitish, pale green, massif green, bluish-green, pale blue, grey-blue, brown, sometimes

             pink or yellow

Transparency : translucent

Lustre : vitreous or nacreous

Hardness : 5 to 5.5

Density : 4.10 to 4.65

R.I. : 1.621 – 1.849

Birefringence : 0.228

Uniaxial negative

System : trigonal

Calamine designates above all a hydro silicate of zinc ( Si0₂ in stead of C0₂ )

SMOKY QUARTZ :
Quartz of yellow-brown, brown to black colour.

Called also Morion or Cairngorm (variety from Scotland).

SMOKY TOPAZ :

Prohibited appellation for a Smoky quartz .

SOAPSTONE :

(English) Synonym for steatite or agalmatolite .

SODA-JADEITE :

See diopside -jadeite .

SODALITE :

Mineral of the group of the feldspathoides ; generally found massif .

Na₈C1₂(AlSi0₄)₆  

Physical and optical properties :

Colour : royal blue resembling lapis-lazuli, but with des white, greyish, yellowish, red veins

Transparency : transparent to opaque

Lustre : vitreous

Hardness : 5 to 6

Density : 2.15 to 2.40

R.I. : 1.480 to 1.488

System : cubic

SOIMONITE :

Variety of corundum .

SOLDERED EMERALD :

Name given in England to an emerald doublet .

SOLDIER'S STONE :

(English) Synonym for amethyst .

SOLOMON'S GEM :

English name. Imitation stone known in Roman times, fabricated in Alexandria. It was an imitation in glass, that was green in reflected light and red in transmitted light.

DARKRITE :

Synonym for apatite .

SOMMERVILLITE :

Variety of chrysocolla .

SONNENSTEIN :

German Name for an feldspath aventurine ou sunstone .
Prohibited Appellation for its artificial imitation, known under the name of Goldfluss .

SOOCHOW JADE or SOOCHOO JADE

Prohibited Appellation : originally designating a combination of jade and quartz ; actually designating serpentine, agalmatolite or saponite .

SOUTH AFRICAN JADE :

Prohibited appellation for a green grossular garnet .