Crookesite
A variety of Minerals
What is Crookesite?
Crookesite is a selenide mineral composed of copper and selenium with variable thallium and silver.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Crookesite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Crookesite Localities Map
See where Crookesite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Crookesite
Its chemical formula is reported either as Cu7(Tl, Ag)Se4 or (Cu, Tl, Ag)2Se. It is formed by precipitation from hydrothermal fluids, and contains by mass: 16.3% Tl, 47.3% Cu, 2.9% Ag, and 33.6% Se. Crookesite is an opaque, bluish grey to pink toned brown metallic mineral crystallizing in the tetragonal system. It has a Mohs hardness of 2.5 to 3 and a specific gravity of 6.9.
Quick Facts
Physical Properties
- Color
- Lead Grey
- Hardness (Mohs)
- 2.5 - 3
- Density
- 7.443 g/cm³
Chemical Properties
- Chemical Formula
- Cu7(Tl, Ag)Se4 Formely considered (Cu,Tl,Ag)2Se.
- Elements
- Ag, Cu, Se, Tl
Identify Crookesite Instantly
- Snap a photo, get instant results
- 6,700+ rocks, minerals & crystals
- Discover collecting spots near you
Crookesite FAQs
How do I identify Crookesite?
Crookesite can be identified by its hardness of 2.5 - 3 on the Mohs scale, Lead Grey color. Look for these key characteristics when examining specimens.
What color is Crookesite?
Crookesite typically appears in Lead Grey. Color can vary depending on impurities and formation conditions.
How hard is Crookesite?
Crookesite has a hardness of 2.5 - 3 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the characteristics of crookesite of Crookesite?
Its chemical formula is reported either as Cu7(Tl, Ag)Se4 or (Cu, Tl, Ag)2Se. It is formed by precipitation from hydrothermal fluids, and contains by mass: 16.3% Tl, 47.3% Cu, 2.9% Ag, and 33.6% Se. Crookesite is an opaque, bluish grey to pink toned brown metallic mineral crystallizing in the tetragonal system. It has a Mohs hardness of 2.5 to 3 and a specific gravity of 6.9.
%252FAbenakiite-(ce)-01.jpg&size=small)
