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, 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.