Pietra di paragone
Esquema
Jerarquía
<materials by composition> > inorganic material > rock > igneous rock > <igneous rock by composition> > <igneous rock by composition: chemical> > basic igneous rock > basalt (basic igneous rock)
Descripción
An extremely hard variety of basalt that is jet black in color with a faint steak of mottled white; was often used as a touchstone for metallurgists.
URI original del concepto
Otros términos
- lapis liydius [en]