Borocookeite is a rare lithium-bearing silicate mineral belonging to the chlorite group, characterized by its inclusion of boron. It typically forms thin, micaceous plates or flaky aggregates within complex granitic pegmatites. Collectors look for it associated with other late-stage pegmatite minerals like tourmaline and albite.

Hardness

2-2.5

Mohs

Luster

Pearly

Streak

White

Transparency

Translucent

mineralrareChlorite Group family

Borocookeite

Hardness: 2-2.5
Luster: Pearly
Streak: White
Transparency: Translucent

Is this borocookeite?

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 borocookeite with a known reference. Borocookeite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Borocookeite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Borocookeite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale pink.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy or micaceous aggregates.

Often confused with

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

Often found alongside borocookeite

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

All properties

Chemical formula: Li₂Al₄(Si₃B)O₁₀(OH)₈
Mohs hardness: 2-2.5
Density: 2.7-2.8 g/cm³
Colors: White Colorless Pale Pink
Streak: White
Luster: Pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Platy or Micaceous Aggregates
Cleavage: Perfect Basal
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites
Typical price: $20-100 per specimen

Where rockhounds find borocookeite

Classic worldwide localities

San Piero in Campo, Elba, Italy
Mount Mica, Maine, USA
Siberia, Russia

Field-hunting tip

Look in granite pegmatites country — that is the host setting where borocookeite typically forms. If you start seeing tourmaline, quartz, albite in float, you are in the right ground. Field specimens usually show a platy or micaceous aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify borocookeite?+

Mohs hardness is 2-2.5. It typically shows a pearly luster. The streak is white. Common colors include white, colorless, pale pink.

Where is borocookeite found?+

Notable localities include San Piero in Campo, Elba, Italy; Mount Mica, Maine, USA; Siberia, Russia.

How much is borocookeite worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like borocookeite?+

Borocookeite is most often confused with Cookeite, Muscovite, Lepidolite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with borocookeite?+

Borocookeite commonly co-occurs with Tourmaline, Quartz, Albite, Lepidolite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does borocookeite form in?+

Borocookeite typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is borocookeite used for?+

Borocookeite is used in collector.

Find borocookeite on the map

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