Keiviite-(Y) is a rare yttrium silicate mineral belonging to the thortveitite group. It is typically found as small, tabular crystals within alkaline pegmatites, primarily documented at the type locality in the Keivy Mountains of Russia.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareThortveitite Group family

Keiviite-(Y)

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

Is this keiviite-(y)?

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 keiviite-(y) with a known reference. Keiviite-(Y) 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. Keiviite-(Y) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Keiviite-(Y) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white, yellowish.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: tabular crystals.

Often confused with

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

mineral

Thortveitite

Mohs 6-7

How to tell apart: Thortveitite is the harder of the two (Mohs 6-7 vs. 5).

How to tell apart: Gadolinite-(Y) is the harder of the two (Mohs 6.5-7 vs. 5).

Compare →

Often found alongside keiviite-(y)

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

All properties

Chemical formula: (Y,Yb)₂Si₂O₇
Mohs hardness: 5
Density: 4.8-4.9 g/cm³
Colors: Colorless White Yellowish
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Tabular Crystals
Cleavage: Distinct
Rarity: Rare
Uses: Collector, Scientific Research
Host rock: Alkaline Pegmatites
Typical price: $100-500 per specimen

Where rockhounds find keiviite-(y)

Classic worldwide localities

Keivy Mountains, Kola Peninsula, Russia

Field-hunting tip

Look in alkaline pegmatites country — that is the host setting where keiviite-(y) typically forms. If you start seeing zircon, quartz, feldspar 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 keiviite-(y)?+

Mohs hardness is 5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white, yellowish.

Where is keiviite-(y) found?+

Notable localities include Keivy Mountains, Kola Peninsula, Russia.

How much is keiviite-(y) worth?+

Typical asking prices fall in the range of $100-500 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like keiviite-(y)?+

Keiviite-(Y) is most often confused with Thortveitite, Gadolinite-(Y). A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with keiviite-(y)?+

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

What kind of rock does keiviite-(y) form in?+

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

What is keiviite-(y) used for?+

Keiviite-(Y) is used in collector, scientific research.

Find keiviite-(y) on the map

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