CONCEPT AND DEFINITION

The dimension and covering stones are also called ornamental stones, natural stones, tombstones, dimensional rocks and finishing (ashlar etc.) materials; they include the lithological kinds that can be extracted in blocks or plates, cut in various forms and processed through slabbing, sawing, polishing etc. Their main application fields include isolated pieces, sculptures, table legs and coverings, counters, tombstones and funeral art in general, as well as buildings, standing out the internal and external coverings of walls, floors, pillars, columns, doorsteps etc.

A movement of U$18 billion/year is estimated for the internal markets within producing countries, U$12 billion/year in commerce of raw and refined materials in the international market, such as of U$10 billion/year for business with machinery, equipment, materials, consuming materials and payment of services. The leverage in the activities can be examined when one refers to the world production of ornamental and covering stones involving from 1,5 millions of ton/year, between 1920 to a current level of 65 millions of ton/year.

Such increase was determined by new kinds of use of the ornamental stones in the urban scenarios, mainly referring to covering works, and furthermore to new technologies of extraction, handling, transport and processing of blocks. The technological advances permitted for the time being the good use and diffusion of several non-commercial stones, while the new uses met very interesting and reliable aesthetic and functional solutions in building construction.

Around 80% of the worldwide production is currently transformed into plates and tiles for coverings, 15% slabbed in pieces for funeral art and 5% for other applications. About 60% of the coverings refers to floors, 16% to external fronts, 14% to interiors and 10% to special finishing works.

Marbles represent currently, about 45% of the worldwide production, with 40% due to granites, 5% to the quartzites and similar ones, and 5% to the slates. The participation of granites grew form a level of 15% in 1950, to 22% in 1970, 38% in 1980, until the current 40%, the global demand of stones always increasing, as well as the use of marbles.

The blocks extracted from the quarries present a variable volume between 5 and 8 sq. meters, exceptionally reaching 12 sq. m. However, particularly special materials with high commercial value, allow manipulation of blocks with at least 1 sq m. The standard specified dimensions vary from 2,4x1,2x0,6m (1,73cubic m) to 3,3x1,8x1,5m (8,91cubic m). Stones with unusual parallel partition plans, such as quartztites and slates, are extracted in plates directly from the massive rock formation (rock bulk).

The outstanding marbles are thin pasted, with white and colorful drawings, most appreciated for the statuary art and other isolated pieces of finishing and furniture. Among the granites, the actual best acceptability goes to the active yellow (like Juparaná), white ( Bianco Cardinalle, Cotton, Cashmere) and active multicolor ( Minas South and Bahia), besides, of course, the blue (Bahia Blue and Macaúbas Blue).