The document describes various properties of mineral luster and transparency. It defines 14 different categories of luster - from dull/earthy to metallic. It also defines 3 categories of transparency - transparent, translucent, and opaque. Certain minerals like quartz and calcite can be transparent or translucent depending on chemical impurities. Ulexite has a unique property where it appears opaque from the side but transparent from the top due to its columnar crystal structure.

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

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

3. Waxy
 Like the surface of a candle
 Chalcedony

4. Pearly
 Like a pearl
 Play of colors
 Light
 Talc, muscovite mica

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

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

7. Resinous
 Looks like freshly-broken shellac, usually yellow-
brown
 Sphalerite

8. Adamantine
 High luster, almost brilliant
 “Diamond-like”
 Sphalerite, diamond

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

10. Metallic
 Very shiny, like processed metals
 Highly reflective
 Opaque minerals
 Pyrite, gold, silver

11. Other words describing luster
 Shiny
 Sparkly
 Shimmering
 Opalescent
 Frosted
 Milky

12. Properties of Minerals:
Transparency
Light transmitted through minerals

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

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

15. Opaque
 Can’t see light through it at all when it is sliced
thin
 Rarely used for gemstones
 Metals, gypsum

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