Botswana Exports of granite, porphyry, basalt, sandstone, other monumental or building stone to Zambia was US$6 during 2021, according to the United Nations COMTRADE database on international trade. Botswana Exports of granite, porphyry, basalt, sandstone, other monumental or building stone to Zambia - data, historical chart and statistics - was last updated on May of 2024.