Holfertite is a very rare uranyl titanate mineral found primarily in rhyolite gas cavities. It is most commonly identified by its distinctive radiating clusters of yellow needles that grow in association with topaz and bixbyite.

Hardness

3-4

Mohs

Luster

Vitreous

Streak

Yellow

Transparency

Translucent

mineralrare

Holfertite

Hardness: 3-4
Luster: Vitreous
Streak: Yellow
Transparency: Translucent

Is this holfertite?

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 holfertite with a known reference. Holfertite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Holfertite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Holfertite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: acicular or radiating aggregates of needles.

Often confused with

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

mineral

Uranophane

Mohs 2.5

How to tell apart: Streak differs — Holfertite leaves yellow, Uranophane leaves pale yellow.

Compare →

Often found alongside holfertite

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

All properties

Chemical formula: (UO₂)(TiO₃)·nH₂O
Mohs hardness: 3-4
Density: 4.45 g/cm³
Colors: Yellow Yellow-brown
Streak: Yellow
Luster: Vitreous
Transparency: Translucent
Crystal system: Orthorhombic
Crystal habit: Acicular or Radiating Aggregates of Needles
Cleavage: None Observed
Rarity: Rare
Uses: Collector
Host rock: Rhyolite Cavities
Typical price: $100-500 for micro-specimens

Where rockhounds find holfertite

Classic worldwide localities

Thomas Range, Utah, USA

Field-hunting tip

Look in rhyolite cavities country — that is the host setting where holfertite typically forms. If you start seeing topaz, bixbyite, pseudobrookite in float, you are in the right ground. Field specimens usually show a acicular or radiating aggregates of needles habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify holfertite?+

Mohs hardness is 3-4. It typically shows a vitreous luster. The streak is yellow. Common colors include yellow, yellow-brown.

Where is holfertite found?+

Notable localities include Thomas Range, Utah, USA.

How much is holfertite worth?+

Typical asking prices fall in the range of $100-500 for micro-specimens. Quality, size, and provenance can move individual specimens well outside that range.

Is holfertite safe to handle?+

This mineral is radioactive. Contains uranium; handle with care, wash hands thoroughly after handling, and store in a shielded container to minimize exposure to radiation. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like holfertite?+

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

What minerals are found with holfertite?+

Holfertite commonly co-occurs with Topaz, Bixbyite, Pseudobrookite, Hematite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does holfertite form in?+

Holfertite typically forms in rhyolite cavities. Working float back to the host body is the standard way to chase a fresh occurrence.

What is holfertite used for?+

Holfertite is used in collector.

Find holfertite on the map

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