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Hematite

Last updated: April 2026

An iron oxide with a high metallic luster and a characteristic red-brown streak.

Hematite has a specific gravity of 5.28 and a refractive index of 2.940–3.220, with a Mohs hardness of 5.5–6.5. It is uniaxial −.

Physical & Optical Properties

RI Range2.940–3.220
SG Range4.95–5.30
SG Typical5.28
Hardness (Mohs)5.5–6.5
Crystal SystemTrigonal
Optic CharacterDR Uniaxial (−)
Birefringence0.280
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsBlack
SpeciesHematite
Black

Measured with a polariscope, a refractometer, a hydrostatic balance, a Chelsea filter, a UV torch, a loupe, a darkfield loupe and a spectroscope — step-by-step for each.

Through the refractometer

Hematite no reading — over the limit 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.75 1.80 REFRACTIVE INDEX DORead the scale from bottom to top, then look for theliquid’s own faint line near the top. SEEThe field stays dark, with one faint line near 1.81 thatdoes not move when you change stones. MEANSOver the limit — this stone’s index is above the contactliquid’s own, so the liquid is the last thing the instrumentcan still see. That faint line is your proof the instrumentis working rather than dead. It is a RESULT: it eliminatesevery species below 1.81 in one observation. A field darkwith NO line means something else has gone wrong. Computed from gems.json — edge positions are arithmetic, not drawn. RI increases upward; the field above the boundary is the dark one.

Drawn from the refractive index above, on a 1.40–1.81 scale. How to take this reading.

Through the polariscope

Hematite No reading ANY POSITION — THE STONE BLOCKS THE LIGHT BETWEEN CROSSED POLARS Hematite is opaque, so no light reaches the analyser. The field stays dark in every position — not because the stone is singly refractive, but because the test cannot be run on it at all. SR, DR and aggregate cannot be separated this way. Computed from optic character and transparency in gems.json. A polariscope separates singly refractive, doubly refractive and aggregate — it does not show the optic sign.

Drawn from the optic character and transparency above. A polariscope separates singly refractive, doubly refractive and aggregate; the optic sign needs a conoscope. How to take this reading.

Specific gravity, and what it rules out

Hematite SG 4.95–5.30 WHERE IT SITS, AND WHAT ELSE IS THERE 1.0 2.0 3.0 4.0 5.0 SCALE ENDS AT 5.0 — THIS BAND RUNS PAST IT Nothing else in the reference table shares this range. A careful hydrostatic reading here names Hematite on its own. Computed from the specific-gravity range in gems.json. Hydrostatic weighing — the bench method this site recommends; heavy liquids are toxic and regulated. Faint ticks are the other species in the table.

Drawn from the specific-gravity range above, against every other species in the table. How to take this reading.

Through the dichroscope

Hematite No reading NO LIGHT THROUGH THE STONE Hematite is opaque. A dichroscope reads light that has passed THROUGH the stone, so there is nothing to split and no reading to take — the same limit that rules out the polariscope. Computed from pleochroism and pleochroic colours in gems.json. Window tints are derived mechanically from the colour words, not chosen; a neutral pair depicts no colour at all.

Drawn from the pleochroism above. Two windows that match mean either no pleochroism or the wrong angle — turn the instrument to tell. How the dichroscope compares.

Key Differentiators

Treatments

Measurement Guides

How to Identify a GemstoneHow to Measure Specific GravityHow to Use a RefractometerUV Fluorescence Testing

Identifying a hematite? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.

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Studying for the GIA, FGA, or FEEG practical? Hematite is one of the 132 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.

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