The NASA PDF Space Suit which contains
CSM21 Spacesuits pp 223-228 in the url name mentions beta cloth and beta marquisette several times.
Question: What are they exactly?
INTEGRATED THERMAL METEOROID GARMENT
The integrated thermal meteoroid garment is a many-layered structure laced to the torso limb suit. It is composed of an inner and outer shell of Beta cloth, seven layers of aluminized Kapton film separated by six layers of Beta Marquisette, and a liner of two layers of Neoprene-coated nylon Ripstop. A layer of Chromei-R (a woven metal) is added to the knee, elbow, and shoulders to protect the suit against abrasion. Chromei-R also is used to protect the garment's boot from abrasion. The boot is attached to the space suit boot by loop tape.
This fits over both the thermal meteoroid garment boot and the suit boot and is used for extravehicular activity. It consists of an insulation and liner, and an outer shell. The liner is Teflon-coated Beta cloth and the insulation is 13 layers of aluminized Kapton film separated by 12 layers of Beta Marquisette. The sole portion contains two additional layers of Beta felt interspaced between the uppermost film and spacer layers. The outer shell features a silicone rubber sole sewn to a laminated structure made up of four layers of two-ply Beta Marquisette. Chromei-R is used as the outer layer of the shell, except for the tongue, which is Teflon coated Beta cloth.