Mineral Luster and Transparency

1. Properties of Minerals: Properties of Minerals:
LusterLuster
The way light reflects off of the The way light reflects off of the
surface of a mineralsurface of a mineral

2. Dull/EarthyDull/Earthy
Very dullVery dull
Mainly in minerals that are porousMainly in minerals that are porous
Kaolinite, orthoclaseKaolinite, orthoclase

3. WaxyWaxy
Like the surface of a candleLike the surface of a candle
ChalcedonyChalcedony

4. PearlyPearly
Like a pearlLike a pearl
Play of colorsPlay of colors
LightLight
Talc, muscovite micaTalc, muscovite mica

5. SilkySilky
Has a shiny surface like a piece of silk clothHas a shiny surface like a piece of silk cloth
Some varieties of gypsum, ulexite, and in fibrous Some varieties of gypsum, ulexite, and in fibrous
mineralsminerals

6. Glassy/vitreousGlassy/vitreous
Looks like glassLooks like glass
Quartz, many rock-forming minerals, obsidianQuartz, many rock-forming minerals, obsidian

7. ResinousResinous
Looks like freshly-broken shellac, usually yellow-Looks like freshly-broken shellac, usually yellow-
brownbrown
SphaleriteSphalerite

8. AdamantineAdamantine
High luster, almost brilliantHigh luster, almost brilliant
““Diamond-like”Diamond-like”
Sphalerite, diamondSphalerite, diamond

9. Sub-MetallicSub-Metallic
Silvery or metallic luster but mineral is Silvery or metallic luster but mineral is
transparent or translucent when in small sliverstransparent or translucent when in small slivers
HematiteHematite

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

11. Other words describing lusterOther words describing luster
ShinyShiny
SparklySparkly
ShimmeringShimmering
OpalescentOpalescent
Frosted Frosted
MilkyMilky

12. Properties of Minerals: Properties of Minerals:
TransparencyTransparency
Light transmitted through mineralsLight transmitted through minerals

13. TransparentTransparent
Clear – you can see right through it when it is sliced Clear – you can see right through it when it is sliced
thinthin
Called “gemmy” because it is desirable for gemstonesCalled “gemmy” because it is desirable for gemstones
Celestite, quartz (rock crystal), seleniteCelestite, quartz (rock crystal), selenite

14. TranslucentTranslucent
See shapes and shadows through it when it is See shapes and shadows through it when it is
sliced thinsliced thin
Chemical impurities can cause the minerals to be Chemical impurities can cause the minerals to be
cloudycloudy
Calcite, quartz, sphaleriteCalcite, quartz, sphalerite

15. OpaqueOpaque
Can’t see light through it at all when it is sliced Can’t see light through it at all when it is sliced
thinthin
Rarely used for gemstonesRarely used for gemstones
Metals, gypsumMetals, gypsum

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