| Table 1. Minerals that are soft enough to work with
HSS lathe tools: |
|
| Mineral |
Color |
Formula |
Hardness |
Comments |
|
| |
|
|
(Mohs) |
|
|
| Azurite |
deep blue |
Cu3(CO3)2(OH)2 |
3.5-4 |
|
|
| Calcite |
colorless; white |
CaCO3 |
3 |
|
|
| Chrysacolla |
blue-green |
Cu4Si4H4O10(OH)10 |
2-4* |
|
|
| Fluorite |
various |
CaF2 |
4 |
look for deep purple |
|
| Hematite
powder |
orange-red |
Fe2O3 |
5.5-6.5** |
|
|
| Malachite |
green |
Cu2CO3(OH)2 |
3.5-4 |
|
|
| Manganosite |
green |
MnO |
5.5** |
|
|
| Rhodochrosite |
pink |
MnCO3 |
3.5-4 |
|
|
| Zincite |
dark red |
ZnO |
4 |
|
|
| |
|
|
| *May be
harder because of impurities. My
sample from Craft Supplies USA destroyed HSS edges. |
|
| **Although
these are hard, they can be worked with HSS tools because they are fine
powders. |
|
| |
|
|
| |
|
|
| Table 2.
Minerals that should be covered with CA glue or epoxy: |
|
| Mineral |
Color |
Formula |
Hardness |
Comments |
|
| |
|
|
(Mohs) |
|
|
| Abalone shell |
mother-of-pearl |
CaCO3 |
3 |
|
|
| Chalcopyrite |
greenish gold |
CuFeS2 |
3.5-4 |
|
|
| Hematite
(specular) |
metallic |
Fe2O3 |
5.5-6.5 |
|
|
| Lapis
(lazurite) |
medium blue |
(Na,Ca)8(AlSiO4)6(SO4,S,Cl)2 |
5-5.5 |
may include pyrite
grains |
|
| Pyrite |
brassy gold |
FeS2 |
6-6.5 |
"fools
gold" |
|
| Turquoise |
blue-green |
CuAl6(PO4)4(OH)8.4H2O |
6 |
|
|
| Cinnabar |
red |
HgS |
2.5 |
***contains mercury! |
|
| Erythrite |
pink |
Co3(AsO4)2.8H2O |
1.5-2.5 |
***contains arsenic |
|
| Orpiment |
yellow |
As2S3 |
1.5-2 |
***contains arsenic |
|
| Realgar |
orange |
AsS |
1.5-2 |
***contains arsenic |
|
| Vanadinite |
yellow to red |
Pb5(VO4)3Cl |
3 |
***contains lead,
vanadium |
|
| Wulfenite |
orange-red |
PbMnO4 |
3 |
***contains lead |
|
| ***These
contain one or more poisonous elements! |
|
|
| |
|
|
| |
|
|
|
|
|
|
|
|