Buffalo Head Hills kimberlite field grained, and well bedded, with high bedding angles. The reworked kimberlite is well sorted, distinctly bedded, and contains abraded olivine grains. Multiple layers of pyroclastic and reworked kimberlite separated by layers of marine mudstone are present at some pipes. These represent a series of discrete kimberlite eruption events separated by quiescent periods during which the muds were deposited. The majority of the BHH kimberlites are diamondiferous, in contrast to those of the Birch Mountains kimberlite field to the northeast which are mostly barren of diamonds. Based on petrography and whole-rock geochemistry, the BHH pipes are classed as Group 1A kimberlites.
Gemstone Gemstone A gemstone (also called a gem, fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli and opal) and occasionally organic materials that are not minerals (such as amber, jet, and pearl) are also used for jewelry and are therefore often considered to be gemstones as well. Most gemstones are hard, but some soft minerals are used in jewelry because of their luster or other physical properties that have aesthetic value. Rarity is another