7/03/2012

Porphyry Introduction


Porphyry has been known and used since ancient times. Important relics and monuments in porphyry have been discovered at Assyrian-Babylonian, Egyptian and Roman sites. In Roman times the red porphyry, so called for its purple-red colour (in Latin “porphyra”) was a symbol of great prestige and majesty.


The name porphyry was initially used to indicate a rock extracted in Egypt, known in ancient times as Imperial Red Porphyry or Ancient Red Porphyry. It was extracted in the Egyptian desert in the mountain Jebel Dhokan (up to 500 A.D.) and it was used to build columns, vases, sarcophagus, busts, etc.

The Romans exploited intensely the quarries, using thousands of workers: the large number of works extended all over the Empire. This stone has always had a great symbolic value: the emperors, personifying divinity, lived surrounded by porphyry, they were born in rooms cladded with porphyry (which existed only in the palaces of power) and many Roman emperors were even buried in sarcophagi of porphyry.

Another famous porphyry of ancient times is the Green Porphyry, found in Greece, in Laconia area, close to the city of Sparta; it was also called Serpentine Porphyry. It was easily recognisable by the presence of crystals of light green feldspar in an olive green matrix.

The production cycle consists of three phases:
* Separation of the rock from the quarry face (quarrying)
* Primary sorting and transport (grading)
* Working of the material

The quarrying was in the open air (not underground like in mines): the porphyry was separated from the face with levers of wood or metal, which were inserted in the natural strata of the rock, causing the fall of slabs. Explosives were rarely used.This material was sorted by manual labourers on the base of thickness and size; then it was transported in barrows or carts pulled by hand to the “work benches” to be worked.

Working with mallets, chisels and iron hammers, cubes, blocks and tiles of varying sizes were produced. The products were loaded by hand onto carts, pulled by mules, and then transported to the railway station of Trento. The 30s are characterised by technological progress, especially in the transport of raw and finished material, using iron carts on rails, cables and the first Lorries.

These were also the years when the use of explosives became the principal method for separating the slabs from the quarrying face, using the “mina a fornello” technique, which replaced the previously used methods. The use of explosives meant that a greater volume of rock could be quarried, producing larger quantities of raw material to be worked with less manpower. At that time all the production of porphyry in Trentino represented 70-80% of the national production.

In the early 60s the Local Council realised the importance of the porphyry to the local economy and this led it to favour local companies. The increase in the number of companies interested in the extraction and working of the porphyry combined with the expansion of the market (especially in central and southern Italy) led to a dramatic increase in production and a progressive improvement in the equipment and techniques of quarrying in the 1960s and 70s. These years saw a continuous growth in the use of machinery, mechanical buckets, lorries, pneumatic hammers.

At the beginning of the 1970s there was another phase of growth in this sector, with the setting up of new companies and the introduction of new machines, which cut the cubes and the tiles, as well as an increase in the mechanization of the quarrying phase and transport. At the same time the search was on for new, larger markets, towards Germany, Austria, Switzerland, France and overseas towards Anglo-Saxons countries.

Our information:

Leeca Stone Co.,Ltd
Add:Xidong Industrial Zone, Shijing Town, Nan'an City, Fujian Province,China

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