What is basalt? and for what is basalt used?
The Oberkassel basalt industry
basalt industry on the right side of the river Rhein 

The Oberkassel quarry families and their company's
1. Adrian
2. Peter Uhrmacher
3. Sen. Christian Uhrmacher's basalt comp. at Oberkassel, "Rheinische Provinzial-Basalt-Werke"
4. Rudolf Uhrmacher - Uhrmacher brothers, Christian Uhrmacher & sons - Jean Uhrmacher,
    limitel partnership

5. Berghovener Ley / heirs Gabriel Uhrmacher
6. Further small company's

The history of the "Adrian" family
The history of the "Uhrmacher" family
Shield of the Uhrmacher family
The human of Oberkassel
Sources and bibliographies