Which country of the tropical north leads in mining and producing emeralds?

ecuador

venezuela

guyana

colombia

Option: Colombia

Explanation:

Columbia is one of the countries that produce two-third of the emerald of the world. The most famous deposit in Colombia is the Muzo Mine and Chivor mine which lies in the northwest and northeast of Bogota in Columbia. Emerald is a gemstone of medium or darker green color. The green color obtains through the impurities of vanadium or chromium.    

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.

experiments.

surveys.

questionnaires.

interviews.

case studies.

participant and non-participant observation.

observational trials.

studies using the delphi method.