Name the essential soil forming minerals- iron oxides:

Name the essential soil - forming minerals silicates:

Which of the minerals are of greatest density?

Amethyst is purple quartz. Smoky quartz is black. Citrine quartz is yellow or orange. Which property of quartz is described?

Distribute the minerals according the groups

Distribute the minerals according the specific gravity: 

Point on the pyrite’s formula:

Choose primary minerals:

Which is the hardness of topaz by Mohs’ scale?

Choose the formula gypsum: