Melkovite is a rare hydrous calcium iron molybdate phosphate mineral typically found in the oxidation zones of hydrothermal molybdenum deposits. It occurs as small, delicate yellow to yellowish-green crystals, often forming radial or fibrous aggregates on matrix.

Hardness

Mohs

Luster

Dull to waxy

Streak

Yellow

Transparency

Transparent

mineralrare

Melkovite

Hardness: ~3
Luster: Dull to waxy
Streak: Yellow
Transparency: Transparent

Is this melkovite?

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 melkovite with a known reference. Melkovite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: dull to waxy.
4
Match the color range
Compare against the expected color range: brownish yellow, lemon.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: pulverulent.

Often confused with

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

mineral

Ferrimolybdite

Mohs 1-2

How to tell apart: Melkovite is noticeably harder (Mohs ~3 vs. 1-2); streak differs, so Melkovite leaves yellow, Ferrimolybdite leaves pale yellow; luster reads dull to waxy on Melkovite and adamantine to silky, earthy on Ferrimolybdite.

How to tell apart: Streak differs, so Melkovite leaves yellow, Powellite leaves light yellow; luster reads dull to waxy on Melkovite and subadamantine, resinous, pearly on Powellite.

Compare →

Often found alongside melkovite

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

All properties

Chemical formula: CaFe₂Mo₅O₁₀(PO₄)₂(OH)₁₂·8H₂O
Mohs hardness: ~3
Density: 2.969-2.973 g/cm³
Colors: Brownish yellow Lemon
Streak: Yellow
Luster: Dull to waxy
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Pulverulent
Cleavage: One, perfect
Rarity: Rare
Uses: Collector
Host rock: Localized along joints in sandstone, formed by alteration of molybdenite in the oxidized zone of small molybdenite-fluorite deposits

Where rockhounds find melkovite

Classic worldwide localities

Shunak Mountains, 60 km west of the Mointy railroad station, Kazakhstan (type locality)
Su Senargiu, Sardinia, Italy

Field-hunting tip

Where it forms: Localized along joints in sandstone, formed by alteration of molybdenite in the oxidized zone of small molybdenite-fluorite deposits. If you start seeing fluorite, molybdenite, magnetite in float, you are in the right ground. Typical habit: pulverulent. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify melkovite?+

Mohs hardness is ~3. Luster: dull to waxy. The streak is yellow. Common colors include brownish yellow, lemon.

Where is melkovite found?+

Notable localities include Shunak Mountains, 60 km west of the Mointy railroad station, Kazakhstan (type locality); Su Senargiu, Sardinia, Italy.

What rocks look like melkovite?+

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

What minerals are found with melkovite?+

Melkovite commonly co-occurs with Fluorite, Molybdenite, Magnetite, Powellite, Ferrimolybdite, Iriginite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does melkovite form in?+

Where it forms: Localized along joints in sandstone, formed by alteration of molybdenite in the oxidized zone of small molybdenite-fluorite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is melkovite used for?+

Melkovite is used in collector.

Find melkovite on the map

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