Mendeleevite-(Ce) is an extremely rare and complex silicate mineral found in the alkaline pegmatites of the Lovozero Massif. Collectors prize it for its unique composition and association with other rare-earth minerals, though it is usually found as small, dark, radioactive crystal aggregates.

Hardness

Mohs

Luster

Vitreous

Streak

Yellowish-brown

Transparency

Translucent

mineralrareTundrite Group family

Mendeleevite-(Ce)

Hardness: 5
Luster: Vitreous
Streak: Yellowish-brown
Transparency: Translucent

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Is this mendeleevite-(ce)?

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-(ce) with a known reference. Mendeleevite-(Ce) sits at Mohs 5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Mendeleevite-(Ce) leaves a yellowish-brown streak.
3
Read the luster
Hold the specimen under a strong light. Mendeleevite-(Ce) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: dark brown, black, reddish-brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, aggregates.

Often confused with

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

mineral

Steenstrupine-(Ce)

Mohs 4

How to tell apart: Mendeleevite-(Ce) is noticeably harder (Mohs 5 vs. 4); streak differs — Mendeleevite-(Ce) leaves yellowish-brown, Steenstrupine-(Ce) leaves yellowish brown.

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Often found alongside mendeleevite-(ce)

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

All properties

Chemical formula: K₄Li₁₇Ca₆REE₁₆(Si₂O₇)₄(PO₄)₆O₂(OH)₃F₂
Mohs hardness: 5
Density: 4.69 g/cm³
Colors: Dark Brown Black Reddish-brown
Streak: Yellowish-brown
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Tabular Crystals, Aggregates
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Alkaline Pegmatites
Typical price: $200-800 per specimen

Where rockhounds find mendeleevite-(ce)

Classic worldwide localities

Kola Peninsula, Russia
Lovozero Massif, Russia

Field-hunting tip

Look in alkaline pegmatites country — that is the host setting where mendeleevite-(ce) typically forms. If you start seeing microcline, aegirine, nepheline in float, you are in the right ground. Field specimens usually show a tabular crystals, aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify mendeleevite-(ce)?+

Mohs hardness is 5. It typically shows a vitreous luster. The streak is yellowish-brown. Common colors include dark brown, black, reddish-brown.

Where is mendeleevite-(ce) found?+

Notable localities include Kola Peninsula, Russia; Lovozero Massif, Russia.

How much is mendeleevite-(ce) worth?+

Typical asking prices fall in the range of $200-800 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is mendeleevite-(ce) safe to handle?+

This mineral is radioactive. Contains significant amounts of thorium, handle with care and wash hands after handling; store away from other minerals to prevent radioactive damage to sensitive specimens. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like mendeleevite-(ce)?+

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

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

Mendeleevite-(Ce) commonly co-occurs with Microcline, Aegirine, Nepheline, Eudialyte. Spotting any of these in float or country rock is a useful trip signal.

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

Mendeleevite-(Ce) typically forms in alkaline pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is mendeleevite-(ce) used for?+

Mendeleevite-(Ce) is used in collector.

Find mendeleevite-(ce) on the map

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