Asbestos type insulating board

Found this recently, it probably is asbestos and will have it lab tested. I am not familiar with asbestos in this form, what can you tell me about it? The return air was panned with this product and is not used, as the forced air furnace was replaced with a hydronic boiler many years ago.

Asbestos Insulated Board 010 (Small).jpg

Asbestos Insulated Board 008 (Small).jpg

Asbestos Insulated Board 006 (Small).jpg

yep see lots a that stuff around here, even 4x8 sheets behind wood stoves and such.

Any specifics about the product? Where and when it was manufactured?

**Asbestos Millboard - **

Asbestos Millboard was used in the construction of walls and ceilings, particularly around furnaces and wood-burning stoves where insulation and fire protection was required. Most varieties of asbestos millboard typically contained between 80 and 85 percent asbestos.
In 1977, the use of asbestos in most construction materials was banned by the Consumer Product Safety Commission. The ban was enacted due to the known dangers of this substance. Asbestos fibers, when inhaled into the lungs or otherwise ingested, can potentially cause diseases such as asbestosis and mesothelioma, both of which have very high mortality rates. These diseases are most commonly caused by long-term asbestos exposure over several years, but mesothelioma has been known to be caused by even very short term exposure.
The presence of materials such as asbestos millboard in your home is not necessarily a cause for alarm. These materials are safe as long as they are in good condition and are not disturbed. Asbestos is dangerous only if fibers are releasing into the air and are able to be inhaled into the lungs.
If your home was built during or before the 1980s, it is possible it may have been built using asbestos millboard or other asbestos-containing construction materials. While materials that are intact and in good condition pose little danger, it is important to know whether asbestos-containing materials exist in your home so that you monitor the condition of the materials. It is particularly important to find out if you are planning to remodel or renovate, as this is likely to cause disturbances that may release asbestos fibers into the air.
More info-----

Thanks, I had never seen return air ducting panned with AIB Asbestos Insulating Board or Millboard. It evidently came in larger sheets and was scored and broke to size. What a poor choice:( I remember a fellow an old HVAC guy who used to say how they had 50lb bags of the stuff and dumped it in barrels and added water to mix to insulate furnaces, boilers, piping and ductwork…Poor fellow.