Struvite-(K) is a rare phosphate mineral occurring in environments rich in organic matter and phosphates. Collectors typically encounter it as small, fragile, tabular to wedge-shaped crystals that are highly sensitive to dehydration. Proper storage in a cool, sealed container is essential to prevent the crystals from crumbling into powder.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrareStruvite Group family

Struvite-(K)

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this struvite-(k)?

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 struvite-(k) with a known reference. Struvite-(K) sits at Mohs 2, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: tabular crystals, wedge-shaped crystals.

Often confused with

Struvite-(K) vs. its common look-alikes, and how to tell them apart in the field.

How to tell apart: Newberyite is the harder of the two (Mohs 3-3.5 vs. 2).

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Often found alongside struvite-(k)

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

All properties

Chemical formula: KMg(PO₄)·6H₂O
Mohs hardness: 2
Density: 1.864 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Orthorhombic
Crystal habit: Tabular crystals, wedge-shaped crystals
Cleavage: None
Rarity: Rare
Uses: Collector, Scientific research
Host rock: Of either late hydrothermal or secondary origin (Switzerland); an alteration product of animal bones and circulating fluids (Austria)

Where rockhounds find struvite-(k)

Classic worldwide localities

Lengenbach, Binntal, Switzerland, Austria
Rossblei, Schladminger Tauern, Styria, Austria

Field-hunting tip

Where it forms: Of either late hydrothermal or secondary origin (Switzerland); an alteration product of animal bones and circulating fluids (Austria). If you start seeing rathite, dolomite, newberyite in float, you are in the right ground. Typical habit: tabular crystals, wedge-shaped crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify struvite-(k)?+

Mohs hardness is 2. Luster: vitreous. The streak is white. Common colors include colorless.

Where is struvite-(k) found?+

Notable localities include Lengenbach, Binntal, Switzerland, Austria; Rossblei, Schladminger Tauern, Styria, Austria.

What rocks look like struvite-(k)?+

Struvite-(K) is most often confused with Struvite, Newberyite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with struvite-(k)?+

Struvite-(K) commonly co-occurs with Rathite, Dolomite, Newberyite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does struvite-(k) form in?+

Where it forms: Of either late hydrothermal or secondary origin (Switzerland); an alteration product of animal bones and circulating fluids (Austria). Working float back to the host body is the standard way to chase a fresh occurrence.

What is struvite-(k) used for?+

Struvite-(K) is used in collector, scientific research.

Find struvite-(k) on the map

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