Thanks everybody. Indeed it's a lovely yelowish wood. Let me translate from Wikipedia in spanish:
"El petiribí o peteribí (Cordia trichotoma) es un árbol maderable valioso, endémico de Sudamérica: Bolivia, Ecuador, Paraguay, Brasil, Argentina."
The Peteribí or Peterebí (Cordia trichotoma) is a valuable wood-workable endemic tree from South America: Bolivia, Ecuador, Paraguay, Brasil and Argentina.
It's named differently in several countries:
IN BRASIL: Louro Pardo, Louro Amarelo, Louro do Sul.
IN PARAGUAY: Peterivy, Peteribí Hú o Guajayvi Hu.
IN BOLIVIA: Piquana Blanca.
IN ARGENTINA: Loro *****, Loro Amarillo, Guajayvi Hu, Peterebí Saiyú or simply Peteribí.
A mail stamp was edited in Argentina with the picture of the tree.