Knorringite is a rare chromium-rich garnet found primarily as inclusions in diamonds or as indicator minerals in kimberlite pipes. It is highly valued by geologists for its role as a geobarometer for the upper mantle, though it is seldom found in well-formed crystals large enough for traditional lapidary.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Semitransparent

mineralrareGarnet Group family

Knorringite

Hardness: ~7
Luster: Vitreous
Streak: White
Transparency: Semitransparent

No image

Is this knorringite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch knorringite with a known reference. Knorringite sits at Mohs ~7, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: blue green, green.
5
Look at form & habit
Crystal system: cubic. Typical habit: equant, dodecahedral, trapezohedral.

Often confused with

Knorringite vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside knorringite

Minerals reported to co-occur with knorringite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Mg₃Cr₂(SiO₄)₃
Mohs hardness: ~7
Density: 3.756 g/cm³
Colors: Blue green Green
Streak: White
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Cubic
Crystal habit: Equant, dodecahedral, trapezohedral
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific research
Host rock: A rare component of ultramafic kimberlite nodules (Kao kimberlite pipe, Lesotho)

Where rockhounds find knorringite

Classic worldwide localities

Red Ledge mine, Nevada Co., California, USA
Kao kimberlite pipe, Lesotho

Field-hunting tip

Where it forms: A rare component of ultramafic kimberlite nodules (Kao kimberlite pipe, Lesotho). If you start seeing olivine, enstatite, chromian diopside in float, you are in the right ground. Typical habit: equant, dodecahedral, trapezohedral. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify knorringite?+

Mohs hardness is ~7. Luster: vitreous. The streak is white. Common colors include blue green, green.

Where is knorringite found?+

Notable localities include Red Ledge mine, Nevada Co., California, USA; Kao kimberlite pipe, Lesotho.

What rocks look like knorringite?+

Knorringite is most often confused with Pyrope, Uvarovite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with knorringite?+

Knorringite commonly co-occurs with Olivine, Enstatite, Chromian diopside, Chromian pyrope, Chromian spinel, Ilmenite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does knorringite form in?+

Where it forms: A rare component of ultramafic kimberlite nodules (Kao kimberlite pipe, Lesotho). Working float back to the host body is the standard way to chase a fresh occurrence.

What is knorringite used for?+

Knorringite is used in collector, scientific research.

Find knorringite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.