Ferricerite-(LaCa) is a rare member of the allanite group, typically identified by its dark, submetallic luster and monoclinic crystal habits. It is frequently found as an accessory mineral in rare-earth-rich pegmatites and granitic rocks.

Hardness

5.5-6

Mohs

Luster

Submetallic

Streak

Grayish-brown

Transparency

Opaque

mineralrareAllanite Group family

Ferricerite-(LaCa)

Hardness: 5.5-6
Luster: Submetallic
Streak: Grayish-brown
Transparency: Opaque

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Is this ferricerite-(laca)?

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 ferricerite-(laca) with a known reference. Ferricerite-(LaCa) sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: grayish-brown.
3
Read the luster
Hold the specimen under a strong light. Luster: submetallic.
4
Match the color range
Compare against the expected color range: black, brownish-black, dark brown.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals, massive, granular.

Often confused with

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

mineral

Allanite

Mohs 5.5-6

How to tell apart: Streak differs, so Ferricerite-(LaCa) leaves grayish-brown, Allanite leaves gray.

How to tell apart: Streak differs, so Ferricerite-(LaCa) leaves grayish-brown, Epidote leaves grayish white; luster reads submetallic on Ferricerite-(LaCa) and vitreous, pearly, somewhat resinous on Epidote.

How to tell apart: Streak differs, so Ferricerite-(LaCa) leaves grayish-brown, Monazite leaves white; luster reads submetallic on Ferricerite-(LaCa) and resinous on Monazite.

Compare →

Often found alongside ferricerite-(laca)

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

All properties

Chemical formula: (La₆Ca₃)□Fe(SiO₄)₃(SiO₃OH)₄(OH)₃
Mohs hardness: 5.5-6
Density: 3.8-4.2 g/cm³
Colors: Black Brownish-black Dark brown
Streak: Grayish-brown
Luster: Submetallic
Transparency: Opaque
Crystal system: Monoclinic
Crystal habit: Tabular crystals, massive, granular
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: pegmatites, granites, skarns

Where rockhounds find ferricerite-(laca)

Classic worldwide localities

Sweden
Norway
Russia
USA

Field-hunting tip

Where it forms: pegmatites, granites, skarns. If you start seeing feldspar, quartz, biotite in float, you are in the right ground. Typical habit: tabular crystals, massive, granular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ferricerite-(laca)?+

Mohs hardness is 5.5-6. Luster: submetallic. The streak is grayish-brown. Common colors include black, brownish-black, dark brown.

Where is ferricerite-(laca) found?+

Notable localities include Sweden; Norway; Russia; USA.

Is ferricerite-(laca) safe to handle?+

Contains thorium and rare earth elements; radioactive, store away from other sensitive minerals and handle with care, washing hands thoroughly after contact.

What rocks look like ferricerite-(laca)?+

Ferricerite-(LaCa) is most often confused with Allanite, Epidote, Monazite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ferricerite-(laca)?+

Ferricerite-(LaCa) commonly co-occurs with Feldspar, Quartz, Biotite, Zircon. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ferricerite-(laca) form in?+

Where it forms: pegmatites, granites, skarns. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ferricerite-(laca) used for?+

Ferricerite-(LaCa) is used in collector.

Find ferricerite-(laca) on the map

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