Because they have a bluish tinge to their colour.
sarsens
Stonehenge phase 1 is the circular earth works that forms the outer part of the monument. The sarsen stones and blue stones are in the center of the earthworks.
The blue stones at Stonehenge came from the Prescelly mountains in south Wales.
There are 92 stones at Stonehenge at the present time
Stonehenge
No, visitors are not allowed to touch the stones at Stonehenge.
The prehistoric monument of Stonehenge
It is believed that all the stones in Stonehenge weigh over 320 tons.
There are other round circles of standing stones in the UK but there is only one called "Stonehenge" near Amesbury, Wiltshire
Stonehenge consists of a circular setting of large standing stones, known as sarsens, topped by lintel stones in the center. The outer circle is surrounded by a circular earthwork bank and ditch. There are also avenues of stones leading away from the main structure.
Stonehenge is an ancient monument. It consists of standing stones built in a circle. It is unclear and unpublished as to exactly how many stones make up Stonehenge.
its called Stonehenge