Comparison · Minerals vs Quartz Family
Magnetite vs Quartz
Magnetite and Quartz are easy to confuse. Quartz is harder (Mohs 7) than Magnetite (Mohs 5.5–6.5), so Quartz will scratch Magnetite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Below is a side-by-side comparison of their properties and the quick tests that separate them.
Key differences between Magnetite and Quartz
- Quartz is harder (Mohs 7) than Magnetite (Mohs 5.5–6.5), so Quartz will scratch Magnetite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
- Streak color differs: Magnetite leaves a black streak on unglazed porcelain, Quartz leaves white.
- Luster is different: Magnetite is metallic to submetallic/dull while Quartz is vitreous, greasy on fracture surfaces.
- Magnetite feels noticeably heavier for its size (specific gravity 5.17–5.2 versus 2.65 for Quartz).
- Hold a thin edge to the light: Magnetite is Opaque, Quartz is Transparent to translucent.
- They overlap in black and gray, but Quartz also comes in clear, purple, yellow, pink, and brown.
- Well-formed crystals give it away: Magnetite is Cubic, Quartz is Trigonal.
Magnetite vs Quartz properties
| Property | Magnetite | Quartz |
|---|---|---|
| Type | Minerals | Quartz Family |
| Mohs hardness | 5.5–6.5 | 7 |
| Luster | Metallic to submetallic/dull | Vitreous, greasy on fracture surfaces |
| Streak | Black | White |
| Transparency | Opaque | Transparent to translucent |
| Specific gravity | 5.17–5.2 | 2.65 |
| Crystal system | Cubic | Trigonal |
| Common colors | Black, Iron-black, Gray-black | Colorless, White, Purple (amethyst), Yellow (citrine), Pink (rose), Brown/black (smoky) |
| Rarity | common | common |
| Typical specimen value | $2–$150+ | $5–$250+ |
Which is more valuable?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $20 for Magnetite, and premium Quartz can reach $250 or more.
About Magnetite
Magnetite is an iron oxide mineral, Fe3O4, crystallizing in the cubic system and the most strongly magnetic naturally occurring mineral on Earth, capable of attracting steel objects and even acting as a natural compass in its lodestone form. It forms in a remarkably wide range of igneous, metamorphic, and sedimentary environments, making it one of the most common accessory minerals in rock-forming systems worldwide. Ancient sailors and travelers used naturally magnetized lodestone, a variety of magnetite, as the earliest known compasses.
About Quartz
Quartz is silicon dioxide, SiO2, one of the most abundant minerals in Earth's continental crust, crystallizing in the trigonal division of the hexagonal crystal system with a hardness of 7 that makes it a standard reference point on the Mohs scale. Its six-sided prismatic crystals, often terminated by pyramidal points, are among the most recognizable crystal shapes in mineralogy. Quartz occurs in nearly every rock type and geologic setting, from granite pegmatites to sedimentary sandstones to hydrothermal veins.
Magnetite vs Quartz FAQ
Is Magnetite the same as Quartz?
No. Magnetite is a mineral while Quartz is a quartz family. Quartz is harder (Mohs 7) than Magnetite (Mohs 5.5–6.5), so Quartz will scratch Magnetite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
How can you tell Magnetite from Quartz?
Quartz is harder (Mohs 7) than Magnetite (Mohs 5.5–6.5), so Quartz will scratch Magnetite and not the other way round. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Streak color differs: Magnetite leaves a black streak on unglazed porcelain, Quartz leaves white. Luster is different: Magnetite is metallic to submetallic/dull while Quartz is vitreous, greasy on fracture surfaces.
Which is harder, Magnetite or Quartz?
Quartz is harder: Mohs 7 against Mohs 5.5–6.5 for Magnetite.
Which is more valuable, Magnetite or Quartz?
Quartz is usually the more valuable of the two: a typical collector specimen runs about $35 against $20 for Magnetite, and premium Quartz can reach $250 or more.
