Siudaite is an extremely rare member of the eudialyte group typically found in agpaitic pegmatites on the Kola Peninsula. It most commonly occurs as small, tabular, yellow-tinted crystals in association with other rare alkaline minerals. Identification usually requires professional analysis due to its striking similarity to other eudialyte-group members.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareEudialyte Group family

Siudaite

Hardness: 5-6
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this siudaite?

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 siudaite with a known reference. Siudaite sits at Mohs 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. Siudaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Siudaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellowish-brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: tabular crystals.

Often confused with

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

Often found alongside siudaite

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

All properties

Chemical formula: Na₁₄Ca₆(Mn,Fe)₃Zr₃Si₂₆O₇₄(OH,Cl)₄·nH₂O
Mohs hardness: 5-6
Density: 2.88 g/cm³
Colors: Yellow Yellowish-brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Tabular Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Agpaitic Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find siudaite

Classic worldwide localities

Kola Peninsula, Russia

Field-hunting tip

Look in agpaitic pegmatites country — that is the host setting where siudaite typically forms. If you start seeing aegirine, microcline, nepheline 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 siudaite?+

Mohs hardness is 5-6. It typically shows a vitreous luster. The streak is white. Common colors include yellow, yellowish-brown.

Where is siudaite found?+

Notable localities include Kola Peninsula, Russia.

How much is siudaite 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 siudaite?+

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

What minerals are found with siudaite?+

Siudaite commonly co-occurs with Aegirine, Microcline, Nepheline, Lomonosovite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does siudaite form in?+

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

What is siudaite used for?+

Siudaite is used in collector.

Find siudaite on the map

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