Sanidine: サニディン (Japonese)
Etymology: from the Greek "sanida" = board, in reference to its tabular morphology
Sanidine is a potassic feldspar that is only found in acid effusive rocks.
Hardness: 6.
See the gallery
Sapphire
Saphir (French), Saphir (German), Zafiro (Spanish), Zaffiro (Italian), 蓝宝石
(Chinese),
サファイア (Japanese)
Chemical formula: Al2 O3.
Hardness: 9.
Ethymology: From the Greek sappheiros”, azure blue.
The word “sapphire” without any colour adjective refers to blue sapphire.
There are sapphires of all colours. Sapphire belongs to the family of corundum, as ruby does. Red corundum specimens are known as rubies and blue ones as sapphires. All other corundum gems are called “fancy sapphires” with a prefix used to denote the gem’s colour.
Thus, yellow corundum must be called “yellow sapphire”, pink corundum “pink sapphire”, green corundum “green sapphire”, purple corundum “purple sapphire”, etc.
Sapphire has a hardness of nine, it is the second hardest gemstone after diamond. Therefore it belongs to the list of so-called “precious stones” (diamond, ruby, sapphire and emerald).
See the gallery of sapphires from Ceylon->
See the gallery of sapphires from Burma->
See the gallery of sapphires from France->
Yellow sapphire 
See the gallery->
Star sapphire 
See the gallery->
Orange Sapphire
See the gallery->
Padparadsha sapphire 
The name "padparadsha" is coming from sanscrit "Flower of lotus".
Sapphirine:
Chemical formula:(Mg,Al)8 (Al,Si)6 O20
Harndess 7.5. 
Discovered in 1819 by Giesecke
Etymology: its name comes from its blue sapphire-like colour (sapphire being the blue variety of corundum)
Type locality: Fiskenaesset, Nuuk Area, Groenland
See the gallery->
Scapolite スカポライト (Japanese)
From the Greek skapos, “shaft”, this reminds that it is usually found in prismatic crystals.
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Scheelite: 灰重石 (japanese)
Chemical formula: Ca WO4
Etymology : in honour of the Swedish chemist Karl Wilhelm Scheele (1742-1786).
Discovered in 1821 in Lns, Sweden, by Wilhelm SCHEELE (1742-1786 ).
See the gallery->
Scolecite:
Chemical formula:(CaAl2Si3O103(H2O) 
Silicate, tectosilicate from the Zeolite group.
Etymology: From the Greek, σκώληξ skolec = ’worm’ in reference to the mineral’s reaction to the blowpipe flame. Scolecit was described in 1813 by A.F. Gehlen et J.N. von Fuchs
Mohs scale: 5-5.5
Crystal system: Monoclinic
See the gallery->
Serendibite:
Discovered in 1902 by Prior and Coomaraswamy
Etymology: from ancient Arabic Serendib, “Ceylon”
Type locality: Gangapitija, Ambakotte, Sri Lanka
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Sekaninaite
Etmology : named after a Czech mineralogist, professor Josef Seknina (1901- ),
Discovered in 1968 by Stanek & Miskovsky in Dolni Bory, Moravia, Czech Republic
This rare gemstone is a collector’s item.
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Shikote Alin:
Shikhote Alin is a place in Siberia where a meteorite fell.
This meteorite fell on 12th February 1947 at 10:38 am on the west part of the Shikote Alin Moutains, close to the village of Passeka, in the west part of the Shikote Alin mountains (in the South East of Siberia).
The sound of the burst was heard for 300km around the point of impact. The meteorite came out of the north and entered the atmosphere at an angle of 41°. A 30km smoke trail remained visible in the sky for several hours. The meteorite entered the atmosphere at a speed of 14.5km/s, the largest part broke up at an estimated altitude of 10km.
The largest specimen, which is on display in Moscow, weighs 1.75 metric ton, out of a total of about 70 metric tons.
This meteorite is composed of an iron/nickel alloy, it is classified as Ogg IIB 5.9% Ni / 0.42% Co / 0.46% P / 0.28% S / 52 ppm Ga / 161 ppm Ge / 0.03 ppm Ir.
See the gallery->
Seraphinite 
(or clinochlore)
Seraphinite is a rock belonging to the chlorite group. It comes from the Baïkal Lake area in Russia.
See the gallery->
Siderite
Chemical formula: Fe+2 CO3
Etymology: From the Greek, meaning iron, in reference to its percentage of iron.
From the Latin ‘minera ferri alba spathiformis” = spathic iron ore.
Sillimanite
Etymology: Named after American chemist and geologist Benjamin Silliman (1779-1864) in 1824.
See the gallery->
Sinhalite: シンハライト (Japanese)
Chemical formula:Mg Al BO4
Etymology: takes its name from the Sanskrit Sinhala, meaning Ceylon.
Sinhalite was discovered in 1952 by Claringbull at Lns in Sri Lanka.
Simpsonite: 
Etymology: dedicated to E.S. Simson.
Simsponite was discovered in 1938 in Tabba Tabba in Western Australia.
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Smaara: Name of the place where a meteorite fell
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Spessartite: スペサルタイト(Japanese)
See Garnet - Spessartite
Smithsonite: スミソナイト (Japanese)
Chemical formula: Zn CO3, Zinc Carbonate
Etymology : named in honour of the mineralogist James Smith, founder of the Smithsonian Institute
Smithsonite was discovered by Beudant in 1832 in Mendips, Derbyshire, England.
Smithsonite can be found in several colours; white, green, blue, pink, lavender blue, red...
The blue colour is due to copper (Cu2+), the pink one to cobalt (Co2+)
Smithsonite is usually found in botryoidal masses, i.e. in cluster-shaped crystals.
See the gallery->
Sodalite: ソーダライト (Japanese)
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Sphalerite:(Zn,Fe)S スファレライト (Japanese)
From the Greek Sphaleros, deceptive, in reference to the possible confusion with galena.
Discovered in 1847 by Glocker.
Synonym for “Blende”.
Sphalerite can be found in many shades ranging from yellow to red, especially in Spain, but also in green colour (rarer) in Bulgaria and Congo.
It is usually found in association with pyrite, galena and chalcopyrite (“BPGC facies”).
See the gallery->
Sphène ou Titanite: スフェーン (チタナイト) (Japanese)
Etymology: from the Greek for “corner” because of its corner-shaped crystals. Sphene is a synonym for Titanite because of its high percentage of titan.
See the gallery->
Spinel: Spinellle (French), Espinela (Spanish), Spinello (Italian), Spinell (German), スピネル (japanese), 尖晶石 (Chinese),шпинелево (Russian)
Chemical formula: Mg Al2 O4
The Spinel was discovered in 1546 by Agricola.
Etymology: From the Latin Spina, “thorn”, in reference to its thorn-shaped with sharp edges crystals.
The spinel has been used in many sets of jewels because it was thought to be ruby. The most famous confusion is the Black Prince’s Ruby, on the Royal Crown of England. For a long time, this 170ct “ruby” has been considered as the biggest ruby worldwide... until it was found to be spinel.
This confusion came from the fact that all red gemstones used to be considered as rubies (from the Latin rubeus, “ red”) or as carbuncles (from the Latin carbunculus, “small ember”).
The spinel can be found in many shades (red, pink, purple, blue).
Anecdote: A few years ago, I was selling swirled gemstones on an Italian mineralogical stock exchange. I had been conscientiously looking for the Italian translations and displayed the price per gram for all my gemstones. I had found Spinella as the Italian translation for Spinel, which made my customers laugh: indeed, in Italian, spinella is a slang term for “joint”.
See the galleries->Voir galeries
Red Spinel_ Blue Spinel_ White Spinel_ Orange Spinel_ Violet Spinel - Purple
Spodumène ou Tryphane:
Chemical formula: LiAlSi2O6
Belongs to the Pyroxene group.
Green pyroxene is called Hiddenite.
Pink pyroxene is called Kunzite.
Staurolite: スタウロライト(Japanese)
Etymology: from the Greek Stauros, “cross” and lithos, “stone”.
Discovered by Karsten in 1800.
See the gallery->
Staurotide:
From the Greek Stauros, meaning cross-shaped.
Sugilite:
Etymology: named in 1976 in honour of its discoverer, Ken Ichi Sugi (1901 - 1948), a Japanese mineralogist.
sugilite was discovered in 1944 on the Iwagi Island, Ehime Prefecture: Shikohu, Japan.
Sunstone:
Trade name given to some feldspar: first to reddish labradorites, usually cabochon cut, coming from Sri-Lanka, and then to red Labradorite from Oregon (USA) known as “Oregon Sunstone”.
Some people also use this term for red andesine.
Synthetic gemstones:
A lot of gemstones have been imitated or synthetically man-reproduced. A synthetic gemstone has the same physical and chemical qualities than natural gemstones, and is often remarkably pure.
Some synthetic gemstones are very difficult to identify and only a gemmologist can classify them properly.
The most important market for synthetic gemstones is in Bangkok. Many jewels sold to tourists in Bangkok are embellished with synthetic stones. If there is no identification information available for a stone, remember that a beautiful ruby or sapphire is never cheap, and that it is easier to make a false gem-lab certificate than a synthetic gemstone!
