Looks like cellulose or wool insulation, asbestos has fiberglass looking crystals in it.
Protect yourself anyways.
Gloves, mask, etc.
It looks like mineral wool, which in my experience has not been asbestos, but the only way to be sure is to have it tested.
If you want a definitive answer based on just a picture, I am sure some one will be along to give which ever answer you are looking for.
These recommendations are applicable to all work involving fiber glass, rock wool and slag wool products.
Wear Appropriate Clothing
Loose-fitting, long-sleeved and long-legged clothing is recommended to prevent irritation.
A head cover is also recommended, especially when working with material overhead.
Gloves are also recommended. Skin irritation cannot occur if there is no contact with the skin.
Do not tape sleeves or pants at wrists or ankles.
Remove Synthetic Vitreous Fiber (SVF) dust from the work clothes before leaving work to reduce potential for skin irritation.
Wear Appropriate Personal Protective Equipment
To minimize upper respiratory tract irritation, measures should be taken to control the exposure. Such measures will be dictated by the work environment and may include appropriate respiratory protective equipment. See OSHA’s Respiratory Protection Standard.
When appropriate, eye protection should be worn whenever SVF Products are being handled.
Personal protective equipment should be properly fitted and worn when required.
Removal of Fibers From the Skin and Eyes
If fibers accumulate on the skin, do not rub or scratch. Never remove fibers from the skin by blowing with compressed air.
If fibers are seen penetrating the skin, they may be removed by applying and then removing adhesive tape so that the fibers adhere to the tape and are pulled out of the skin.
SVF may be deposited in the eye. If this should happen, do not rub the eyes. Flush them with water or eyewash solution (if available). Consult a physician if irritation persists.
Minimize Dust Generation
Keep the material in its packaging as long as practical and if possible.
Tools that generate the least amount of dust should be used. If power tools are to be used, they should be equipped with appropriate dust collection systems as necessary.
Keep work areas clean and free of scrap SVF material.
Do not use compressed air for clean up unless there is no other effective method. If compressed air must be used, proper procedures and control measures must be implemented. Other workers in the immediate area must be removed or similarly protected.
Where repair or maintenance of equipment that is either insulated with SVF or covered with settled SVF dust is necessary, clean the equipment first with HEPA vacuum equivalent (where possible) or wipe the surface clean with a wet rag to remove excess dust and loose fibers. If compressed air must be used proper procedures and control measures must be implemented. Other workers in the immediate area must be removed or similarly protected.
Avoid unnecessary handling of scrap materials by placing them in waste disposal containers and keep equipment as close to working areas as possible to prevent the release of fibers.
Maintain Adequate Ventilation
Unless other proper procedures and control measures have been implemented, dust collection systems should be used in manufacturing and fabrication settings where appropriate and feasible.
Exhausted air containing SVFs should be filtered prior to recirculation into interior workspaces.
If ventilation systems are used to capture SVFs, they should be regularly checked and maintained.
To learn more, see the following NAIMA Publications:
Facts #62: Health and Safety Facts for Fiber Glass (N040)
Play It Smart, Play It Safe DVD (N049)
Facts #63: Health and Safety Facts for Rock and Slag Wool (N041)
NAIMA Product Stewardship Program Pocket Folder (N052)
Working Smart with Fiber Glass, Rock Wool and Slag Wool Products (N059)
Working Smart with Fiber Glass, Rock Wool and Slag Wool Products (N059SP)
Facts #78: Exposure Data For Fiber Glass, Rock Wool & Slag Wool (N062)
Lick it and tell us what it tastes like.
It's the only way to be sure.
Can only tell with polarized-light microscopy.
The insulation probably not but the sheetrock in the 50's was full of asbestos.
Edited to add: vinyl flooring too!