CAD Chart, page-122

yeah aircore is only good for your softer sedimentary rocks generally shallow holes. For deeper results/ harder ground you’d use RC, as the hammer and more air pressure allow you to drill deeper at a good production rate but it’s more expensive then aircore. Then you would use a diamond rig for more targeted work for eg where they believe there is something worth looking at/ geotechnical work or for your deeper holes. Diamond drilling cost per metre is very high.
this is what makes there accelerated POW to get a diamond rig in ASAP very very interesting.