Description: Chlorite describes a group of silicates similar in structure to micas; the name is based on the Greek word for “green,” which refers to chlorite’s typical color. Like micas, chlorites have a strong cleavage in one direction that commonly gives them a foliated appearance. They are often described as having an "oily" feel. Only a general chemical formula is typically used, because there are a number of elements that substitute for one another.

Chlorites are common in low grade metamorphic rocks, a characteristic mineral of the greenschist facies. Chlorite minerals are also an alteration product, most often formed in environments where other minerals are altered by heat, pressure, and chemical activity. Temperatures don't have to be extreme (less than a few hundred degrees) nor pressures (within just a few miles of Earth's surface) for chlorites to form. An example environment for chlorites could be where oceanic crust descends into a subduction zone.

Color: Various shades of green. Rarely yellow, white, pink, black

Streak: Pale green to grey

Luster: Vitreous, pearly, dull

Fracture: Irregular/Uneven

Cleavage: Perfect, in one direction

Hardness: 2 - 2½ on Moh’s scale

Density/Specific Gravity: 2.6 - 3.3 g/cm³

Distinguishing Physical Properties:

• Hardness: Chlorite is so soft that it can be scratched by a fingernail.

• Color: Green, and the powder generated by scratching is green (don't, lab specimens already look bad)

• Crystals: The plates are flexible, but not elastic like mica

• Feel: It feels oily when rubbed between the fingers