Diamonds have long been mined from alluvial terrace deposits within the rainforest of Guyana, South America. No primary kimberlite deposits have been discovered in Guyana, nor have there been previous studies on the mineralogy and origin of the diamonds. Paleoproterozoic terranes in Guyana are prospective to diamond occurrences because the most productive deposits are associated spatially with the eastern escarpment of the Paleoproterozoic Roraima Supergroup. Geographic proximity suggests that the diamonds are detrital grains eroding from the <1.98 Ga conglomerates, metamorphosed to zeolite and greenschist facies. The provenance and paragenesis of the alluvial diamonds are described using a suite of placer diamonds from different locations across the Guiana Shield. Guyanese diamonds are typically small, and those in our collection range from 0.3 to 2.7 mm in diameter; octahedral and dodecahedral, with lesser cubic and minor macle forms. The diamonds are further subdivided into those with abraded and non-abraded surfaces. Abraded diamonds show various colors in cathodoluminescence, whereas most non-abraded diamonds appear blue. In all populations, diamonds are predominantly colorless, with lesser brown to yellow and very rare white. Diamonds are predominantly Type IaAB and preserve moderate nitrogen aggregation and total nitrogen concentrations ranging from trace to ~1971 ppm. The kinetics of nitrogen aggregation indicate mantle-derived residence temperatures of 1124 ± 100 °C, assuming residence times of 1.3 and 2.6 Ga for abraded and non-abraded diamonds, respectively. The diamonds are largely sourced from the peridotitic to eclogitic lithospheric upper mantle based on both δ13C values of –5.82 ± 2.45‰ (VPDB-LSVEC) and inclusion suites predominantly comprised of forsterite, enstatite, Cr-pyrope, chromite, rutile, clinopyroxene, coesite, and almandine garnet. Detrital, accessory minerals are non-kimberlitic. Detrital zircon geochronology indicates diamondiferous deposits are predominantly sourced from Paleoproterozoic rocks of 2079 ± 88 Ma.

The granitoid and greenstone-hosted 9 Mile Deposit, located in the Paleoproterozoic Barama-Mazaruni Greenstone Belt of the Guiana Shield, is one of a series of gold deposits within the NW-SE trending Makapa-Kuribrong Shear Zone (MKSZ), which extends from Venezuela, through Guyana, and French Guiana. The 9 Mile Deposit is underlain by the upper section of a shallowly-dipping meta-rhyolite rock, which was intruded by a host granodiorite and subsequently intruded by of a series of mafic dykes. Auriferous quartz veins are associated with the NE-SW thrust which was crosscut by a steep E-W shear zone, at least 12 km in length. Field relationships and lithogeochemical data suggest that the granodiorite was crustally derived and emplaced in a volcanic arc or syn-to late-collisional setting. U-Pb (SHRIMP II) dating of zircons indicates the granodiorite intruded at approximately 2.15, Ga suggesting it is a local representative of a regional suite of syn-to late-tectonic granitoid plutons emplaced during the main phase of Trans-Amazonian Orogeny.

ituated on the northern edge of South America, Guyana (figure 1) is the continent's only English-speaking nation. Originally, Guyana was populated by the first nations of Akawaio, Carib, Patamona, Lokono, Macushi, Pemon, Waiwai, Wapishana, and Warao. Dutch, French, and finally English colonialism brought advances in agriculture and technology. Sadly, these advances were also intertwined with the violent history of transatlantic slavery and indentured servitude. Laborers from Ghana, Togo, India, China, and Portugal were brought to Guyana, either by force or voluntarily. The colonial economy was based on the cultivation of sugarcane throughout the nineteenth and twentieth centuries. Guyana's legacy of colonialism has been one of violence, racism, and poverty, which peaked during the social upheavals of the 1960s (Spencer, 2007). It has been difficult for Guyana to fully divorce itself from its colonial past. However, Guyana today is a peaceful and diverse mix of cultures and ethnic groups from around the world. This little melting pot of different languages, clothing styles, cuisines, traditional dance, and music has birthed a culture that is distinctly Guyanese (Rodney, 1981;Ishmael, 2013; https://guyanatourism.com).Guyana's population is concentrated near the coastal deltas. Most of the population is engaged in agriculture, as the tropical climate, flat terrains, and fertile soils support sugarcane and rice cultivation. The scenery becomes increasingly pristine as one moves inland. Cultivated plains and infrastructure give way to tropical rainforests and rolling hills carpeted by the Amazon jungle. The country's western boundary is dominated by the towering, flat-topped tepuis of the Roraima Mountains (figure 2). It is within the mountainous northwest where most of the diamond deposits are located. The lead author,

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