Properties of Properties of Minerals: LusterMinerals: Luster

The way light reflects off of The way light reflects off of the surface of a mineralthe surface of a mineral

Dull/EarthyDull/Earthy

Very dullVery dull Mainly in minerals that are porousMainly in minerals that are porous Kaolinite, orthoclaseKaolinite, orthoclase

WaxyWaxy

Like the surface of a candleLike the surface of a candle ChalcedonyChalcedony

PearlyPearly

Like a pearlLike a pearl Play of colorsPlay of colors LightLight Talc, muscovite micaTalc, muscovite mica

SilkySilky

Has a shiny surface like a piece of silk Has a shiny surface like a piece of silk clothcloth

Some varieties of gypsum, ulexite, and Some varieties of gypsum, ulexite, and in fibrous mineralsin fibrous minerals

Glassy/vitreousGlassy/vitreous

Looks like glassLooks like glass Quartz, many rock-forming minerals, Quartz, many rock-forming minerals,

obsidianobsidian

ResinousResinous

Looks like freshly-broken shellac, Looks like freshly-broken shellac, usually yellow-brownusually yellow-brown

SphaleriteSphalerite

AdamantineAdamantine

High luster, almost brilliantHigh luster, almost brilliant ““Diamond-like”Diamond-like” Sphalerite, diamondSphalerite, diamond

Sub-MetallicSub-Metallic

Silvery or metallic luster but mineral Silvery or metallic luster but mineral is transparent or translucent when is transparent or translucent when in small sliversin small slivers

HematiteHematite

MetallicMetallic Very shiny, like processed metalsVery shiny, like processed metals Highly reflectiveHighly reflective Opaque mineralsOpaque minerals Pyrite, gold, silverPyrite, gold, silver

Other words describing Other words describing lusterluster

ShinyShiny SparklySparkly ShimmeringShimmering OpalescentOpalescent Frosted Frosted MilkyMilky

Properties of Properties of Minerals: Minerals:

TransparencyTransparencyLight transmitted through Light transmitted through

mineralsminerals

TransparentTransparent Clear – you can see right through it when Clear – you can see right through it when

it is sliced thinit is sliced thin Called “gemmy” because it is desirable for Called “gemmy” because it is desirable for

gemstonesgemstones Celestite, quartz (rock crystal), seleniteCelestite, quartz (rock crystal), selenite

TranslucentTranslucent See shapes and shadows through it See shapes and shadows through it

when it is sliced thinwhen it is sliced thin Chemical impurities can cause the Chemical impurities can cause the

minerals to be cloudyminerals to be cloudy Calcite, quartz, sphaleriteCalcite, quartz, sphalerite

OpaqueOpaque

Can’t see light through it at all when Can’t see light through it at all when it is sliced thinit is sliced thin

Rarely used for gemstonesRarely used for gemstones Metals, gypsumMetals, gypsum

UlexiteUlexite Ulexite appears to be Ulexite appears to be

opaque when you look opaque when you look at it from the side, but at it from the side, but when you look at it when you look at it from the top, it is from the top, it is transparent. This is transparent. This is because light is able to because light is able to travel up the perfectly travel up the perfectly straight columnar straight columnar crystals. It’s sometimes crystals. It’s sometimes called “T.V. rock” called “T.V. rock” because of this special because of this special property.property.