Geological ErasGeological Eras
| Era | Period |
|---|---|
| quaternary | 12,000bc - present |
| pleistocene | 600,000bc - 12,000bc |
| tertiary | 65,000,000bc - 600,000bc |
| pilocene | 10,000,000bc - 600,000bc |
| miocene | 25,000,000bc - 10,000,000bc |
| oligocene | 35,000,000bc - 25,000,000bc |
| eocene | 55 000,000bc - 35 000,000bc |
| paleocene | 65,000,000bc - 55,000,000bc |
| mesozoic | 230,000,000bc - 65,000,000bc |
| cretaceous | 135,000,000bc - 65,000,000bc |
| jurassic | 180,000,000bc - 135,000,000bc |
| triassic | 230,000,000bc - 180,000,000bc |
| plaezoic | 4,500,000,000bc - 230,000,000bc |
| carboniferous II | 300,000,000bc - 230,000,000bc |
| carboniferous I | 345,000,000bc - 300,000,000bc |
| devonian | 405,000,000bc - 345,000,000bc |
| silurian | 425 000,000bc - 405 000,000bc |
| ordovician | 500,000,000bc - 425 000,000bc |
| cambrian | 600,000,000bc - 500,000,000bc |
| precambrian II | 2,000,000,000bc - 600,000,000bc |
| precambrian I | 4,500,000,000bc - 2,000,000,000bc |
Moh's Scale of Hardness
| Standard Hardness | Mineral |
|---|---|
| 1 | Talc |
| 2 | Gypsum |
| 3 | Calcite |
| 4 | Fluorite |
| 5 | Apatite |
| 6 | Feldspar (Orthoclase) |
| 7 | Quartz |
| 8 | Topaz |
| 9 | Corundum |
| 10 | Diamond |
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