Native chromium is an extremely rare native metal that typically occurs as microscopic inclusions within chromite or other ultramafic rocks. Because it is almost never found in hand-sized specimens, it is primarily a target for advanced microscopic mineral collectors and researchers. It is distinguishable from other native metals primarily through laboratory analysis like SEM-EDS.
Is this native chromium?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch native chromium with a known reference. Native Chromium sits at Mohs 7.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: cubic. Typical habit: rarely found as microscopic grains or intergrowths.
Often confused with
Native Chromium vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Native Chromium is noticeably harder (Mohs 7.5 vs. 4-4.5); streak differs, so Native Chromium leaves white, Platinum leaves grayish white.
How to tell apart: Native Chromium is noticeably harder (Mohs 7.5 vs. 4); streak differs, so Native Chromium leaves white, Iron leaves gray.
Often found alongside native chromium
Minerals reported to co-occur with native chromium. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cr
- Mohs hardness
- 7.5
- Density
- 7.17 g/cm³
- Colors
- Streak
- White
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Rarely found as microscopic grains or intergrowths
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In heavy sands derived from the contact metamorphic zone between a siliceous marble and ultramafic rock (Sichuan Province, China); in a kimberlite pipe (Liaoning Province, China)
Where rockhounds find native chromium
Classic worldwide localities
- Sea-floor muds from near the island of Diaoyudao, a few km northeast of Taiwan, at about 1500 m depth, China
- Luobusha ophiolite, 200 km southeast of Lhasa, Tibet, China
- Gavasai ore field, location not further given, Russia
- Unspecified kimberlite pipes in Sakha, Russia
Field-hunting tip
Where it forms: In heavy sands derived from the contact metamorphic zone between a siliceous marble and ultramafic rock (Sichuan Province, China); in a kimberlite pipe (Liaoning Province, China). If you start seeing pyrrhotite, pentlandite, chalcopyrite in float, you are in the right ground. Typical habit: rarely found as microscopic grains or intergrowths. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify native chromium?+
Where is native chromium found?+
What rocks look like native chromium?+
What minerals are found with native chromium?+
What kind of rock does native chromium form in?+
What is native chromium used for?+
Find native chromium on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
