Kegginite is a rare lead calcium arsenic oxide, typically orange-red. Associated minerals include ansermetite, gypsum and mesaite. It was first described from Packrat mine, near Gateway, Mesa County, Colorado, USA.

Hardness

Mohs

Luster

Vitreous

Streak

Pinkish orange

Transparency

Transparent

mineralrare

Kegginite

Hardness: ~2
Luster: Vitreous
Streak: Pinkish orange
Transparency: Transparent

No image

Is this kegginite?

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 kegginite with a known reference. Kegginite 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: pinkish orange.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: orange-red.
5
Look at form & habit
Crystal system: trigonal. Typical habit: microcrystalline aggregates.

Often confused with

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

mineral

Molybdite

Mohs 3-4

How to tell apart: Molybdite is the harder of the two (Mohs 3-4 vs. ~2); streak differs, so Kegginite leaves pinkish orange, Molybdite leaves white; luster reads vitreous on Kegginite and adamantine on Molybdite.

Compare →

Often found alongside kegginite

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

All properties

Chemical formula: Pb₃Ca₃[AsV₁₂O₄₀(VO)]·20H₂O
Mohs hardness: ~2
Density: 2.69 g/cm³
Colors: Orange-red
Streak: Pinkish orange
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Microcrystalline aggregates
Cleavage: Good on {001}
Rarity: Rare
Uses: Collector
Host rock: A secondary mineral found on asphaltumin a montroseite- and corvusite-bearing sandstone in a roll-front type uranium deposit

Where rockhounds find kegginite

Classic worldwide localities

Packrat mine, near Gateway, Mesa County, Colorado, USA

Field-hunting tip

Where it forms: A secondary mineral found on asphaltumin a montroseite- and corvusite-bearing sandstone in a roll-front type uranium deposit. If you start seeing ansermetite, gypsum, mesaite in float, you are in the right ground. Typical habit: microcrystalline aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify kegginite?+

Mohs hardness is ~2. Luster: vitreous. The streak is pinkish orange. Common colors include orange-red.

Where is kegginite found?+

Notable localities include Packrat mine, near Gateway, Mesa County, Colorado, USA.

Is kegginite safe to handle?+

Kegginite contains arsenic, lead and vanadium and calls for real care. Contains lead, which is toxic. Handle with care, wash hands after touching, and avoid creating or inhaling dust.

What rocks look like kegginite?+

Kegginite is most often confused with Molybdite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with kegginite?+

Kegginite commonly co-occurs with Ansermetite, Gypsum, Mesaite, Sherwoodite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does kegginite form in?+

Where it forms: A secondary mineral found on asphaltumin a montroseite- and corvusite-bearing sandstone in a roll-front type uranium deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is kegginite used for?+

Kegginite is used in collector.

Find kegginite on the map

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