Delrioite is a rare hydrated calcium strontium vanadate found primarily in the oxidized zones of vanadium-uranium deposits. It typically forms as delicate, transparent yellow tabular crystals or crusts coating sandstone surfaces. Due to its scarcity and fragility, it is highly sought after by advanced collectors of secondary vanadium minerals.

Hardness

Mohs

Luster

Vitreous to pearly

Streak

Pale yellow green

Transparency

Translucent

mineralrare

Delrioite

Hardness: ~2
Luster: Vitreous to pearly
Streak: Pale yellow green
Transparency: Translucent

No image

Is this delrioite?

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 delrioite with a known reference. Delrioite 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: pale yellow green.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to pearly.
4
Match the color range
Compare against the expected color range: yellow brown, light yellow green, dark green.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: acicular, aggregates, radial.

Often confused with

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

mineral

Pascoite

Mohs ~2.5

How to tell apart: Streak differs, so Delrioite leaves pale yellow green, Pascoite leaves cadmium-yellow.

Often found alongside delrioite

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

All properties

Chemical formula: Sr(VO₃)₂·4H₂O
Mohs hardness: ~2
Density: 3.1 g/cm³
Colors: Yellow brownLight yellow greenDark green
Streak: Pale yellow green
Luster: Vitreous to pearly
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Acicular, aggregates, radial
Cleavage: Distinct on {001}
Rarity: Rare
Uses: Collector
Host rock: An efflorescence on sandstone of the Salt Wash member of the Jurassic Morrison Formation associated with a U–V deposit

Where rockhounds find delrioite

Classic worldwide localities

Jo Dandy mine, Montrose County, Colorado, USA (type locality)

Field-hunting tip

Where it forms: An efflorescence on sandstone of the Salt Wash member of the Jurassic Morrison Formation associated with a U–V deposit. If you start seeing metadelrioite, rossite, metarossite in float, you are in the right ground. Typical habit: acicular, aggregates, radial. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify delrioite?+

Mohs hardness is ~2. Luster: vitreous to pearly. The streak is pale yellow green. Common colors include yellow brown, light yellow green, dark green.

Where is delrioite found?+

Notable localities include Jo Dandy mine, Montrose County, Colorado, USA (type locality).

Is delrioite safe to handle?+

Delrioite contains vanadium. Contains vanadium which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling specimens.

What rocks look like delrioite?+

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

What minerals are found with delrioite?+

Delrioite commonly co-occurs with Metadelrioite, Rossite, Metarossite, Quartz. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does delrioite form in?+

Where it forms: An efflorescence on sandstone of the Salt Wash member of the Jurassic Morrison Formation associated with a U–V deposit. Working float back to the host body is the standard way to chase a fresh occurrence.

What is delrioite used for?+

Delrioite is used in collector.

Find delrioite on the map

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