The art of sculpting stone must have been in full bloom already back then. Sculptures of Zimbabwean birds have been found and now adorn the national flag. The stone was a type of soapstone known as „Springstone“.
Zimbabwe calls a number of unusual stone types its own. The jet-black Nero Assoluto granite is a prime example of commercially important export stone.
http://www.stone-ideas.com/2013/09/04/sculptor-gedion-nyanhongo-has-chosen-love-as-the-central-theme-for-his-artwork/