Al2O3
Corundum is an aluminum oxide mineral of the oxides and hydroxides group, with structural formula Al2O3.
What is the chemical formula of Topaz?
Al₂SiO₄(F,OH)₂
Topaz/Chemical formula
What is the chemical formula for Sapphire?
Al₂O₃
Sapphire/Chemical formula
What crystal system is corundum?
Trigonal
| Corundum | |
|---|---|
| Crystal system | Trigonal |
| Crystal class | Hexagonal scalenohedral (3m) H-M symbol: (3 2/m) |
| Space group | R3c (No. 167) |
| Unit cell | a = 4.75 Å, c = 12.982 Å; Z = 6 |
What is the density of orthoclase?
2.56
Orthoclase Mineral Data
| General Orthoclase Information | |
|---|---|
| Chemical Formula: | KAlSi3O8 |
| Cleavage: | {001} Perfect, {010} Good |
| Color: | Colorless, Greenish, Grayish yellow, White, Pink. |
| Density: | 2.56 |
Is corundum a silicate?
A high density of ~4.0 g/cm3 (most silicate minerals are ~2.6 g/cm3) results in corundum occurring in secondary placer deposits and recoverable by panning methods, similar to how you would recover placer gold. Corundum comes in all colours of the rainbow but is most commonly found as opaque crystals with dull colours.
How is sapphire made?
Corundum is found in igneous rocks. When those are cooling slowly, large crystals of minerals can form from those that are present within the magma. The purest sapphires are formed during the transformation of igneous rocks. The more slowly the magma cools, the larger the sapphires will be.
What is a Blue ruby?
Corundum is an aluminum oxide that commonly forms hexagonal barrel-shaped prisms that taper at both ends or as thin tabular hexagonal plates. Red corundum is called ruby, blue corundum is called sapphire, and all other colours are called fancy sapphires.
