Ключевые слова: africa, agate, amorphous, black, blue, brown, chalcedony, colors, concentric, crystalline, cut, dendrites, drawings, drum, eye, flat, fortress, gemstone, gray, green, landscape, mossy, natural, onyx, orange, parallel, pieces, polished, quartz, quartzite, red, rocks, ruins, stone, strips, structure, together, volcanic,