Most were formed at depths between 150 and 250 kilometers in the Earth's mantle, although a few have come from as deep as 800 kilometers.
ສ່ວນໃຫຍ່ຖືກສ້າງຕັ້ງຂື້ນຢູ່ໃນຄວາມເລິກລະຫວ່າງ 150 ຫາ 250 ກິໂລແມັດໃນກະດານ ຫນ່ວຍ ໂລກ, ເຖິງວ່າມີ ຈໍາ ນວນ ຫນ້ອຍ ຫນຶ່ງ ໄດ້ມາຈາກຄວາມເລິກເຖິງ 800 ກິໂລແມັດ.