Portlandite
A variety of Minerals
What is Portlandite?
Portlandite is an oxide mineral. It is the naturally occurring form of calcium hydroxide (Ca(OH)2) and the calcium analogue of brucite (Mg(OH)2).
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Portlandite 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.
Portlandite Localities Map
See where Portlandite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Formation of Portlandite
Portlandite occurs in a variety of environments. At the type location in Northern Ireland it occurs as an alteration of calc–silicate rocks by contact metamorphism of larnite–spurrite. It occurs as fumarole deposits in the Vesuvius area. In Jebel Awq, Oman it occurs as precipitates from an alkaline spring emanating from ultramafic bedrock. In the Chelyabinsk coal basin of Russia it is produced by combustion of coal seams and similarly by spontaneous combustion of bitumen in the Hatrurim Formation of the Negev desert in Israel and the Maqarin area, Jordan. It also occurs in the manganese mining area of Kuruman, Cape Province, South Africa in the Kalahari Desert where it occurs as large crystals and masses. It occurs in association with afwillite, calcite, larnite, spurrite, halite, brownmillerite, hydrocalumite, mayenite and ettringite. It was first described in 1933 for an occurrence at Scawt Hill, Larne, County Antrim, Northern Ireland. It was named portlandite because the chemical calcium hydroxide is a common hydrolysis product of Portland cement.
Quick Facts
Physical Properties
- Color
- Colourless, light yellow
- Hardness (Mohs)
- 2.5 - 3
- Density
- 2.24 g/cm³
Chemical Properties
- Chemical Formula
- Ca(OH)2
- Elements
- Ca, H, O
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Portlandite FAQs
How do I identify Portlandite?
Portlandite can be identified by its hardness of 2.5 - 3 on the Mohs scale, Colourless color. Look for these key characteristics when examining specimens.
What color is Portlandite?
Portlandite typically appears in Colourless, light yellow. Color can vary depending on impurities and formation conditions.
How hard is Portlandite?
Portlandite 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 formation of portlandite of Portlandite?
Portlandite occurs in a variety of environments. At the type location in Northern Ireland it occurs as an alteration of calc–silicate rocks by contact metamorphism of larnite–spurrite. It occurs as fumarole deposits in the Vesuvius area. In Jebel Awq, Oman it occurs as precipitates from an alkaline spring emanating from ultramafic bedrock. In the Chelyabinsk coal basin of Russia it is produced by combustion of coal seams and similarly by spontaneous combustion of bitumen in the Hatrurim Formation of the Negev desert in Israel and the Maqarin area, Jordan. It also occurs in the manganese mining area of Kuruman, Cape Province, South Africa in the Kalahari Desert where it occurs as large crystals and masses. It occurs in association with afwillite, calcite, larnite, spurrite, halite, brownmillerite, hydrocalumite, mayenite and ettringite. It was first described in 1933 for an occurrence at Scawt Hill, Larne, County Antrim, Northern Ireland. It was named portlandite because the chemical calcium hydroxide is a common hydrolysis product of Portland cement.
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