Mineral inclusions have been recovered from 40 small (<1.5 mm) diamonds from the Sloan 1 and 2 kimberlite pipes in northern Colorado. Primary inclusions (i.e., proto- or syngenetic) are olivine, clinopy-roxene, sanidine, rutile, and possibly native Fe and some phlogopite. Phases interpreted as epigenetic are acmite, richterite, most phlogopite, perovskite, Mn-ilmenite, Cr-spinel, magnetite, calcite, serpentine and possibly Mg-ilmenite. Acmite, richterite, and perovskite have not previously been reported in diamond. The epigenetic minerals commonly occur as inclusion assemblages such as phlogopite + richterite, phlogopite + perovskite + ilmenite + magnetite + serpentine, and phlogopite + clinopyroxene + spinel + magnetite + calcite. The majority of the primary inclusions have an eclogitic suite affinity, which is uncommon but similar to diamonds in the Premier, Orapa, and Mbuji Mayi kimberlites of southern and central Africa and from a few sites in Russia and Western Australia. Secondary inclusions reflect...