Hematite 2" Skull

Hematite
Grounds and protects
Boosts self esteem
Enhances willpower
Stimulates concentration
Helps you come to term with mistakes and accept them as learning experiences rather than disasters
 
Crystal Skulls
Help connect with spirit guides, ancestors, spiritual teachers and ascended masters
Can provide protection and healing when worked with
Can connect with ancient knowledge, as they are record keepers
Assist with channeling guidance
Can be held during meditation
You can also use them as part of a crystal grid
They each have their own personality and when asked, will give you their name
This is just a snippet of information.  There are many good books and articles to provide more information