Blackwood is actually a great tone wood which unfortunately hadn't been developed in Australia. It's now being grown overseas, like China, in plantations as they saw the potential and the impending lack of traditional tone woods due to unsustainable forestry practices.
You can look up on the wood database to see density etc but it should be noted that some less dense woods can end up being heavier as they are very thirsty woods. Silky Oak is very heavy when finished but it's less dense than Blackwood.