Formicaite is an extremely rare calcium formate mineral typically found in environments containing decomposing organic matter and limestone. It usually appears as small, thin, tabular crystals in cavities of sedimentary rocks, often requiring micro-analysis for definitive identification.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Formicaite

Hardness: 2-3
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this formicaite?

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 formicaite with a known reference. Formicaite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Formicaite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Formicaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, yellowish.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals.

Often confused with

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

Often found alongside formicaite

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

All properties

Chemical formula: Ca(HCOO)₂
Mohs hardness: 2-3
Density: 2.23 g/cm³
Colors: White Colorless Yellowish
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular Crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: Fossiliferous Limestone
Typical price: $50-300 per specimen

Where rockhounds find formicaite

Classic worldwide localities

Italy
Germany

Field-hunting tip

Look in fossiliferous limestone country — that is the host setting where formicaite typically forms. If you start seeing calcite, fluorite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify formicaite?+

Mohs hardness is 2-3. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, yellowish.

Where is formicaite found?+

Notable localities include Italy; Germany.

How much is formicaite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like formicaite?+

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

What minerals are found with formicaite?+

Formicaite commonly co-occurs with Calcite, Fluorite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does formicaite form in?+

Formicaite typically forms in fossiliferous limestone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is formicaite used for?+

Formicaite is used in collector.

Find formicaite on the map

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