Mendeleevite-(Nd) is an extremely rare and complex mineral belonging to the mendeleevite group, first discovered in the alkaline pegmatites of the Kola Peninsula. It is typically found as small, colorlessish octahedral crystals that are notably radioactive. Due to its unique chemical composition involving cesium and rare earth elements, it is a highly sought-after specimen for advanced mineral collectors.

Hardness

5-5.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareMendeleevite group family

Mendeleevite-(Nd)

Hardness: 5-5.5
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this mendeleevite-(nd)?

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 mendeleevite-(nd) with a known reference. Mendeleevite-(Nd) sits at Mohs 5-5.5, 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: colorless.
5
Look at form & habit
Crystal system: cubic. Typical habit: octahedral crystals.

Often confused with

Mendeleevite-(Nd) vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside mendeleevite-(nd)

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

All properties

Chemical formula: Cs₆(Nd,REE,Ca)₃₀(Si₇₀O₁₇₅)(OH,F,H₂O)₃₅
Mohs hardness: 5-5.5
Density: 3.20 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Cubic
Crystal habit: Octahedral crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: In a pectolite aggregate in quartz-rich rock associated with a complex alkaline massif

Where rockhounds find mendeleevite-(nd)

Classic worldwide localities

Kola Peninsula (Russia)

Field-hunting tip

Where it forms: In a pectolite aggregate in quartz-rich rock associated with a complex alkaline massif. If you start seeing pectolite, quartz, aegirine in float, you are in the right ground. Typical habit: octahedral crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify mendeleevite-(nd)?+

Mohs hardness is 5-5.5. Luster: vitreous. The streak is white. Common colors include colorless.

Where is mendeleevite-(nd) found?+

Notable localities include Kola Peninsula (Russia).

Is mendeleevite-(nd) safe to handle?+

Mendeleevite-(Nd) contains trace uranium or thorium. Mendeleevite-(Nd) is radioactive due to its thorium and rare earth element content; handle with care and store in a lead-lined or secure container to limit radiation exposure.

What rocks look like mendeleevite-(nd)?+

Mendeleevite-(Nd) is most often confused with Eudialyte. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with mendeleevite-(nd)?+

Mendeleevite-(Nd) commonly co-occurs with Pectolite, Quartz, Aegirine, Fluorite, Khvorovite, Mendeleevite-. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does mendeleevite-(nd) form in?+

Where it forms: In a pectolite aggregate in quartz-rich rock associated with a complex alkaline massif. Working float back to the host body is the standard way to chase a fresh occurrence.

What is mendeleevite-(nd) used for?+

Mendeleevite-(Nd) is used in collector.

Find mendeleevite-(nd) on the map

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