Marsala is available in many levels of sweetness, with dolce providing the best substitute for cream sherry. Madeira, produced on the Portuguese island of the same name, is another viable substitute. In a pinch, sweet vermouth can also be used successfully in many recipes.
First they are all concrete, just different application methods. Gunite (dry nozzle)is a dry mix where water is added at the nozzle. Shotcrete (wet nozzle) is premixed wet. They both use high air pressure to force the mixture to stick to the wall. Just as if you take a ball of mud and throw it at something, if wants to stick.
Re: Helenite..Don't Be Fooled! Helenite is glass in the same sense that natural obsidian is glass. Helenite is synthesized from ash from Mount Saint Helens. It is an absolutely beautiful material - especially the stones that are four carats or more. I own scores of different types of natural gems - including zultanite, color change garnet, apatite. I never - almost never - buy synthetic stones, but helenite is absolutely gorgeous. I have become a fan.