Identification guide · Minerals
How to Identify Goethite
Goethite ranges from yellowish brown to dark brown or black, with a silky, dull, or submetallic luster depending on how it formed, and it commonly appears in botryoidal, stalactitic, or radiating fibrous masses rather than sharp crystals. Its streak is a distinctive yellowish brown, unlike hematite's red streak, and hardness runs about 5 to 5.5. It shows no cleavage in massive form. Goethite is frequently confused with hematite and limonite, with streak color remaining the fastest way to tell them apart.
Goethite identification checklist
| Color | Brown, Yellowish brown, Reddish brown, Black | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Adamantine to dull/earthy, silky | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Opaque, translucent in thin splinters | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 5–5.5 | A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. |
| Streak | Yellowish brown | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | Perfect, one direction | |
| Fracture | Uneven to splintery | |
| Specific gravity | 3.3–4.3 | Heavier than it looks (specific gravity about 3.8). |
| Crystal system | Orthorhombic |
Goethite look-alikes and how to tell them apart
Andradite is harder (Mohs 6.5–7) than Goethite (Mohs 5–5.5), so Andradite will scratch Goethite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Goethite vs Andradite →
Both sit near Mohs 5–5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Goethite vs Eudialyte →
Hessonite is harder (Mohs 6.5–7) than Goethite (Mohs 5–5.5), so Hessonite will scratch Goethite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not. Goethite vs Hessonite →
Goethite is harder (Mohs 5–5.5) than Heulandite (Mohs 3.5–4), so Goethite will scratch Heulandite and not the other way round. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
Goethite identification FAQ
How can you tell if a rock is Goethite?
Check the color (brown, yellowish brown, reddish brown, and black), the adamantine to dull/earthy, silky luster, a Mohs hardness of 5–5.5 and a yellowish brown streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Goethite?
Goethite has a Mohs hardness of 5–5.5. A steel knife blade (Mohs 5.5) scratches it; a copper coin does not.
What is the difference between Goethite and Andradite?
Goethite (Mohs 5–5.5, adamantine to dull/earthy, silky luster) and Andradite (Mohs 6.5–7, vitreous to resinous/adamantine luster) look alike, but hardness, streak and heft usually separate them. See the full Goethite vs Andradite comparison for a side-by-side table.
Is Goethite worth anything?
Entry-level Goethite 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 Goethite?
Goethite is most often brown, yellowish brown, reddish brown, and black. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
