Itsiite is an extremely rare borosilicate mineral discovered in the Itsi Mountains of Yukon, Canada. It typically appears as small, honey-yellow tabular crystals found within skarn deposits associated with boron-rich hydrothermal activity.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Itsiite

Hardness: 4
Luster: Vitreous
Streak: White
Transparency: Transparent

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Is this itsiite?

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 itsiite with a known reference. Itsiite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Itsiite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Itsiite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, brownish-yellow.
5
Look at form & habit
Crystal system: trigonal. Typical habit: tabular crystals.

Often confused with

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

mineral

Gowerite

Mohs 3

How to tell apart: Itsiite is noticeably harder (Mohs 4 vs. 3).

How to tell apart: Danburite is the harder of the two (Mohs 7-7.5 vs. 4).

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Often found alongside itsiite

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

All properties

Chemical formula: Ba₂CaB₄Si₄O₁₆(OH)₂
Mohs hardness: 4
Density: 3.31 g/cm³
Colors: Yellow Brownish-yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Tabular Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Skarn
Typical price: $50-300 per specimen

Where rockhounds find itsiite

Classic worldwide localities

Itsi Mountains, Yukon, Canada

Field-hunting tip

Look in skarn country — that is the host setting where itsiite typically forms. If you start seeing gowerite, danburite, fluorite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify itsiite?+

Mohs hardness is 4. It typically shows a vitreous luster. The streak is white. Common colors include yellow, brownish-yellow.

Where is itsiite found?+

Notable localities include Itsi Mountains, Yukon, Canada.

How much is itsiite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like itsiite?+

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

What minerals are found with itsiite?+

Itsiite commonly co-occurs with gowerite, danburite, fluorite, calcite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does itsiite form in?+

Itsiite typically forms in skarn. Working float back to the host body is the standard way to chase a fresh occurrence.

What is itsiite used for?+

Itsiite is used in collector.

Find itsiite on the map

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