Volcanic stones

Bulk mining and minerals for sale to the best price of the international market

Volcanic stones or pozzolana for sale. Sellers, suppliers and exporters of natural volcanic stones or pozzolana in bulk with the best price from Spain.

Volcanic Stones Or Pozzolana For Sale

The volcanic stones or pozzolana is a natural rock made up of volcanic projections (pyroclasts), it has a scoriaceous and alveolar structure. Its color can be black, gray or red (from brick red to dark brown).

The pozzolana formations currently exploited are mainly “strombolian cones” (accumulation of projections around an emission point forming a regular cone with a slope close to 45º of basaltic type (SiO2 content of 42 to 48%) or leucobasaltic (content in SiO2 from 48 to 52%) and more rarely andesitites.

The volcanic stones or pozzolana

In relation to other natural rocks, the water content of volvanic stone or pozzolana is high and can vary between 8 and 18% depending on the seasons of the year and ambient humidity. The porosity of pozzolan can vary between 40 and 60% of the volume depending on the granulometries. Contrary to what happens with other aggregates, it is the thicker elements that have a more important porosity coefficient.

The 24-hour water absorption tests show that the cellular texture and porosity of the volvanic stones or pozzolana give it a great water absorption capacity, which can vary from 20 to 30% by weight of the dry aggregate. (Test with pozzolana 7/15: water absorption in 24 hours 27% by weight). Normally, under outdoor heap storage conditions, the water content does not exceed 2/3 of the absorption in 24 hours.

In the tests carried out with sand of 0/3 grain size collected in heaps in the open air, the water content varies between 10 and 15% under normal climatic conditions. The melting temperature of pozzolana is 1,140 Cº, but its poor conductivity is such that an element of 15 cm. thick, exposed one of its faces for 8 hours to this heat, the opposite face has a temperature of approximately 80 Cº only. The side exposed to heat becomes vitrified.

Normal Volcanic Stone (Pozzolana)

Natural volcanic stone, with a color that varies between various shades of gray, and a density that ranges from 0.75 to 1.12, depending on the granulometry. The available glanulometries are in millimeters; 0-5; 5-9; 10-25 and 25-50.

Red Volcanic Stone (Pozzolana)

Special natural volcanic stone for use in gardening, with a reddish color, and with a density and range of grain sizes similar to normal pozzolana. The grain sizes referred to are the “standard” ones, 0-5; 0-10…etc, however, and in response to the different needs of our clients, we can offer different ones.


Cement manufacturing: Pozzolana is a siliceous material that, not possessing cementitious properties in itself, contains components that, at ordinary temperatures, combine with lime, in the presence of water, to give compounds of poor solubility and resistant properties. Pozzolanic cement is obtained from mixing clinker with pozzolana and the advantages it offers in relation to the rest are the following:

-Greater durability.

-Improved resistance to sea water.

-Better defense against sulfates and chlorides.

-Increased compression resistance.

-Increased impermeability due to the reduction of cracks during setting.

-Decreased heat of hydration.

-Improved abrasion resistance.

-Increased resistance of steel to corrosion.

-Less need for water.

Thermal Insulator: Given the conductivity of pozzolana in its natural state, with average values less than 0.21 Kcal. /Hm2C, makes this an insulator of great interest.

Light aggregates: For the manufacture of low-density concrete.


For the production of PREFABRICATED PRODUCTS, with the advantage of a lighter average weight and easier maneuverability of the products, blocks, vaults, pipes…

Construction auxiliary: Both in horizontal and vertical construction, served in different granulometries, from the finest: 0-5 mm, to the thickest of 20-50 mm, in addition to the All-one.

Sports Facilities: As natural drainage in soccer fields, for the construction of tennis courts and sports centers.

Natural filters: The great permeability of this volcanic material allows the filtration of liquids, with the great advantage of presenting greater porosity in coarse granulometries.

Absorbents: Its liquid absorption capacity allows its use as an absorbent in industry, as well as in odorous preparations (odorous volcanic soils).

Abrasive: Due to its special characteristics, it is used as an ingredient in the manufacture of abrasive detergents.

Encapsulating: It can also be used as an encapsulating material for hazardous toxic solid waste generated by some industries.


Inert Substrate: The presence of a series of highly favorable parameters for its use as an inert substrate, such as its cation exchange capacity and practically zero electrical conductivity, as well as its PH = 5.5/6, means that it is currently used. as an inert substrate in which, through irrigation water, nutrients and treatments are provided and perfectly controlled, making it possible to carry out exhaustive monitoring of the plant.

Aerator: Given their great stability, durability and low density, these materials are being used as aerants and support for hydroponic crops. Pozzolana alone, or as part of other more compact substrates (heavy topsoil) creates a network of macropores that allows permanent aeration.

Mulching or Padding: This application is about sheltering the soil, protecting it from both frost in winter and water evaporation in summer, preventing the proliferation of weeds and root competition, in addition to reducing maintenance work. Late spring and early summer is the most suitable time to mulch the soil, as this can conserve moisture from spring rains.

volcanic stones or pozzolana
volcanic stones or pozzolana
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