Warwickite is a rare borate mineral that typically forms elongated or prismatic dark-colored crystals in metamorphosed limestones. It is most famous for its occurrence in the contact metamorphic zones of the New York Highlands, where it appears alongside various magnesium-rich silicates.

Hardness

3-4

Mohs

Luster

Submetallic

Streak

Black

Transparency

Opaque

mineralrare

Warwickite

Hardness: 3-4
Luster: Submetallic
Streak: Black
Transparency: Opaque

Is this warwickite?

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 warwickite with a known reference. Warwickite 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. Warwickite leaves a black streak.
3
Read the luster
Hold the specimen under a strong light. Warwickite typically shows a submetallic luster.
4
Match the color range
Compare against the expected color range: black, dark brown, reddish-brown.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: prismatic crystals, elongated, acicular.

Often confused with

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

mineral

Ludwigite

Mohs 5

How to tell apart: Ludwigite is the harder of the two (Mohs 5 vs. 3-4).

How to tell apart: Streak differs, so Warwickite leaves black, Szaibelyite leaves white; luster reads submetallic on Warwickite and dull on Szaibelyite.

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Often found alongside warwickite

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

All properties

Chemical formula: (Mg,Ti,Fe³⁺,Al)₂(O,OH)BO₃
Mohs hardness: 3-4
Density: 3.36-3.41 g/cm³
Colors: Black Dark Brown Reddish-brown
Streak: Black
Luster: Submetallic
Transparency: Opaque
Crystal system: Orthorhombic
Crystal habit: Prismatic Crystals, Elongated, Acicular
Cleavage: Perfect in One Direction
Rarity: Rare
Uses: Collector
Host rock: Metamorphosed Limestone, Skarn Deposits
Typical price: $20-150 per specimen

Where rockhounds find warwickite

Classic worldwide localities

Warwick, New York, USA
Amity, New York, USA
Glenelg, Scotland
Ladoga Lake, Russia

Field-hunting tip

Look in metamorphosed limestone, skarn deposits country, the host setting where warwickite typically forms. If you start seeing spinel, calcite, serpentine in float, you are in the right ground. Field specimens usually show a prismatic crystals, elongated, acicular habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify warwickite?+

Mohs hardness is 3-4. It typically shows a submetallic luster. The streak is black. Common colors include black, dark brown, reddish-brown.

Where is warwickite found?+

Notable localities include Warwick, New York, USA; Amity, New York, USA; Glenelg, Scotland; Ladoga Lake, Russia.

How much is warwickite worth?+

Typical asking prices fall in the range of $20-150 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like warwickite?+

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

What minerals are found with warwickite?+

Warwickite commonly co-occurs with Spinel, Calcite, Serpentine, Chondrodite, Phlogopite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does warwickite form in?+

Warwickite typically forms in metamorphosed limestone, skarn deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is warwickite used for?+

Warwickite is used in collector.

Find warwickite on the map

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