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A scoria cone is a small, steep sided cone, usually with a deep central crater. It is formed by fire containing eruptions of gas rich basalt or andesite magma which reaches the surface without coming into contact with water. Frothy lava thrown high into the air cools to form scoria, which piles up in steep slopes.
An igneous rock that contains abundant vesicles. Scoria is formed when magma rich in dissolved gases is erupted at the earth's surface. At the surface the magma is under less pressure and the gases escape to form bubbles, which are trapped as the magma cools and solidifies.
Vesicles: - small holes formed in a volcanic rock by gas bubbles present when the lava cooled and solidified
Magma: - molten rock material consisting of silicates and dissolved gases such as steam and CO2. It may also contain suspended crystals, or rock fragments from the surrounding rocks. Magma is generated deep in the earth's crust where temperatures are high, and is the source of igneous rocks
- To the south of Lake Taupo lie the active cone volcanoes Tongariro, Ngauruhoe and Ruapehu. Ngauruhoe has been frequently active in recorded times, but has not erupted since 1975. Ruapehu is New Zealand's largest cone volcano and its last eruptions were in 1995-1996.
- The lake covers the world's most destructive volcano, the Taupo volcano.
The Taupo/Tongariro Central Plataeu area contains numerous volcanoes,
including Mt Ngauruhoe, Mt Tongariro & Mt Ruapehu.
- Originally, scoria was the name for the silicate slag left over from the smelting of ore. The word scoria, in fact, stems from the Greek word for refuse or trash. Scoria resembles silicate slag; thus its name.
- A highly expanded form of scoria is called reticulate, where bubble walls have burst, leaving a three dimensional network of glass threads. Because reticulate is so expanded, some people call it basaltic pumice.
- Scoria is usually heavier, darker and more crystalline than pumice.
- Because scoria is very hard and porous, it makes a wonderful base for roads, or used during winter to provide friction for automobiles.
- Mixing scoria into the soil at planting time will help to drain water.
- Coarse grade scoria can be used as BBQ rocks.
- Finer grade scoria is suitable for garden pathways, and ground cover.
The environment is an important consideration for Taupo Scoria. A number of measures are adopted to reduce the effects on the surrounding environment.
As with any business that draws on the earth's natural resources, protecting the environment is an important consideration in planning, developing and operating the quarry.
Taupo Scoria work alongside District and Regional councils and engage independent experts to determine the best methods of extracting and processing the scoria, and work with many expert consultants to ensure all aspects of the quarrying operation meet regulations and care for the surrounding environment.
In New Zealand quarrying companies must ensure that all aspects of the quarry meet the requirements of planning objectives, rules and guidelines set within the framework of the Resource Management Act 1991.
Drilling and blasting is unnecessary at Taupo Scoria as the material has already separated during its ejection from the volcano. The scoria is crushed and screened into various grades from 7mm - 100mm, then stockpiled ready for transportation.
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