Identification guide · Minerals
How to Identify Chlorite
Chlorite appears as dull to pearly green flakes, scales, or earthy coatings, occasionally forming pseudohexagonal crystals in metamorphic rocks. It has one perfect cleavage direction like mica, but the resulting flakes are flexible without being elastic, meaning they do not snap back when bent. Hardness is low, around 2 to 2.5, and streak is pale green to colorless. This flexible-but-inelastic cleavage is the key test separating chlorite from biotite mica, which looks similar but springs sharply back into shape.
Chlorite identification checklist
| Color | Green, Dark green, Blackish green | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous to pearly | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Translucent | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 2–2.5 | A fingernail (Mohs 2.5) scratches it easily. |
| Streak | Pale green to white | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect basal, one direction | |
| Fracture | Uneven across cleavage; flexible non-elastic flakes | |
| Specific gravity | 2.6–3.3 | Ordinary rock-like heft (specific gravity about 2.95), similar to quartz. |
| Crystal system | Monoclinic |
Chlorite look-alikes and how to tell them apart
Both sit near Mohs 2–2.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Chlorite vs Calcite →
Both sit near Mohs 2–2.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Chlorite vs Biotite →
Both sit near Mohs 2–2.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Chlorite vs Glauconite →
Marble is harder (Mohs 3.5) than Chlorite (Mohs 2–2.5), so Marble will scratch Chlorite and not the other way round. A fingernail (Mohs 2.5) scratches it easily.
Chlorite identification FAQ
How can you tell if a rock is Chlorite?
Check the color (green, dark green, and blackish green), the vitreous to pearly luster, a Mohs hardness of 2–2.5 and a pale green to white streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Chlorite?
Chlorite has a Mohs hardness of 2–2.5. A fingernail (Mohs 2.5) scratches it easily.
What is the difference between Chlorite and Calcite?
Chlorite (Mohs 2–2.5, vitreous to pearly luster) and Calcite (Mohs 3, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Chlorite vs Calcite comparison for a side-by-side table.
Is Chlorite worth anything?
Entry-level Chlorite specimens sell for around $2, typical collector pieces about $20, and premium examples $150 or more depending on size, quality and locality.
What color is Chlorite?
Chlorite is most often green, dark green, and blackish green. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
