Guanín was an alloy of copper, gold and silver, similar to red gold, used in pre-Columbian central America. The name is borrowed from the Taíno, who prized it for its reddish-purplish color and unique smell, and associated it with both worldly and supernatural power.
It is a common misconception that pre-Columbian Americas lacked bronze and thus were not able to deploy hardened copper alloys. This misconception may well arise because tin, the common component of Eurasian bronze (although common in Bolivia), is rare in the Caribbean basin.
Notwithstanding, copper, iron, manganese, nickel, chromium, cobalt and zinc mixed into a matrix of iron sulfides and other metal sulfides including gold, cobalt and nickel are readily available, often glittering in as natural ores such as pyrite (fool's gold), the brassy golden yellow cubanite, and marcasite. Deposits of these ores are found on the surfaces of the formerly submerged karst rock formations of these islands.
Guanín may alternatively have been a manganese bronze. Today US "gold dollars" are made of an alloy of 88.5% copper, 6% zinc, 3.5% manganese and 2% nickel, which may be similar to guanin, although nickel would not have been included in guanin due to its high melting point.
Columbus's report of metal axes in lands and seas of the Caribbean, although viewed skeptically by some, cannot be readily dismissed. In this aforecited article, authors attribute this bronze to the Mayans. One might bear in mind the Mayans were trading contacts with the Taínos who used the word guanín to describe the copper-gold alloys they used for ornamental and religious purposes. Additionally there were readily available natural deposits of the necessary ores (see above) in the Major Antilles. The existence of Pre-Columbian era metal tools in the Americas is now considered academic and historical "fact", although the question remains as to which ethnicities, nations or civilizations used these objects. Thus classification of Taíno technological progress as merely Neolithic may well be an misinterpretation awaiting archeological resolution of Taíno use of guanín alloy tools.