The color is very translucent and may exhibit some rainbows when held to the light. These types of stones are particularly good for meditation. Optical Calcite in particular is known to assist one in "seeing" the truth in any situation. These are all "one of a kind" pieces - no two are alike - and they are irregularly shaped. It is VERY IMPORTANT that you cleanse Ice Calcite before using it - simply run it under cool water for a second or so, and then air dry. There can be mining dust on them which must be removed and you want them to shine and sparkle when you use them. The water cleansing is also an energetic practice to "clear" the stones from any energies they picked up on their journey from the earth to your hands. In general, Calcites as a group are strong amplifiers and cleansers of energy. They are great for Feng Shui and keeping the most positive vibrations in a room. They are helpful for promoting spiritual growth and psychic awareness. Calcites are known to balance the intellect and emotions, connecting them for what is called "emotional intelligence."
A crystal slab is a piece of crystal cut into a flat shape, often with natural, unpolished edges. The flat shape makes it easy to display upright on a stand or lay flat on the body. Slabs can show off a crystal's pattern and colors sometimes better than a freeform or tumbled stone as there is more smooth, contiguous surface to look at.