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And mixed in the sand layers are traces of copper, lead, zinc and even barytes that reflect the periods when particular industries were dominant.

There are manufactures of leather gloves and other goods, and in the neighbourhood barytes and coal mines and extensive market gardens.

These are the hard materials to be vitrified by the fluxes, which are carbonate or oxide of lead, boracic acid or borax, potash or soda, carbonate of lime or barytes.

It was composed of flint, potter's clay, carbonate of barytes, and terra ponderosa.

Sandstone, ochre, slate, soapstone, graphite are also mined, and lead, zinc, barytes, gypsum and even diamonds have been discovered but not exploited.