Borate chlorides

Boracite is a magnesium borate mineral with formula: Mg3B7O13Cl. It occurs as blue green, colorless, gray, yellow to white crystals in the orthorhombic - pyramidal crystal system. Boracite also shows pseudo-isometric cubical and octahedral forms. These are thought to be the result of transition from an unstable high temperature isometric form on cooling. Penetration twins are not unusual. It occurs as well formed crystals and dispersed grains often embedded within gypsum and anhydrite crystals. It has a Mohs hardness of 7 to 7.5 and a specific gravity of 2.9. Refractive index values are nα = 1

Hilgardite is a borate mineral with the chemical formula Ca2B5O9Cl·H2O. It is transparent and has vitreous luster. It is colorless to light pink with a white streak. It is rated 5 on the Mohs Scale. It crystallizes in the triclinic crystal system. Crystals occur as distorted tabular triangles and are hemimorphic, polytypes exist.

Chambersite is a manganese borate mineral with formula . It is a member of the borate mineral series that includes other minerals such as ericaite () and boracite (). When chambersite was first discovered, it was the second chemical analogue of boracite to be found in nature. It was discovered as a mineral at Barber's Hill salt dome in Texas in 1957 and in 1971 at the Dongshuichang deposit in Jixian, Tianjin, China. Chambersite occurs associated with the evaporite minerals halite, anhydrite, and gypsum.

Karlite (kar'-lite) is a silky white to light green orthorhombic borate mineral, not to be confused with tremolite-actinolite. It has a general formula of Mg7(BO3)3(OH)4Cl. Karlite is named in honor of Franz Karl (1918–1972), professor of mineralogy and petrography at Christian Albrechts University in Kiel, Germany, for his studies of the geology of the eastern Alps.