silanol group — а functional group in chemistry with the connectivity Si-OH …
sillimanite — species of mineral; see sillimanite in ‘Classification’ …
sinhalite — species of mineral; see sinhalite in ‘Classification’ …
skarn — calcium-bearing silicates of any age …
skutterudite — species of mineral; data; faceted specimens exist …
smithsonite — species of mineral; see smithsonite in ‘Classification’ …
smoky quartz — variety of quartz; see smoky quartz in ‘Classification’ …
snowflake obsidian — variety of obsidian; see snowflake obsidian in ‘Classification’ …
sodalite — species of mineral; see sodalite in ‘Classification’ …
sperrylite — species of mineral; data; faceted specimens exist …
spessartine — species of mineral; see spessartine in ‘Classification’ …
spessartite — synonym of spessartine …
sphalerite — species of mineral; see sphalerite in ‘Classification’ …
spinel — species of mineral; see spinel in ‘Classification’ …
spodumene — species of mineral; see spodumene in ‘Classification’ …
square — a commonly used shape in faceting a gemstone …
square cushion — a commonly used shape in faceting a gemstone …
staurolite — species of mineral; data; faceted specimens exist …
sugilite — species of mineral; see sugilite in ‘Classification’ …
