semi-metals (metalloids)
Nonmetallic elements that are lusterless and solid; they possess a certain amount of electric and thermal conductivity.
tellurium 
Rare semimetal that is used especially in the manufacture of detonators, electric resistors, rubber, ceramics and glass.
antimony 
Semimetal that is used in several alloys (mostly with lead) and especially in making metal for printing type and semiconductors.
selenium 
Semimetal that is usually used in photoelectric cells and semiconductors; it is an indispensable trace element for organisms.
arsenic 
Toxic semimetal that is used especially in very low doses for therapeutic uses and in the manufacture of semiconductors.
germanium 
Rare semimetal that is used especially in the manufacture of electronic devices and in optical equipment (camera and microscope lenses).
silicon 
Most common element on the planet after oxygen; it is used mostly in the manufacture of electronic devices because of its semiconductor properties.
boron 
Semimetal that is used especially as a neutron absorber in nuclear reactors, as a rocket fuel and in detergents.