Hello folks new to this forum but been in the hearth industry for 20 years. Looking for some help with regard to preway air cooled chimney and fireplace. Some moron has gutted the firebox and slid a gas insert in which requires me to remove system and install gas zero. However upon inspection I have found a substance which resembles vermiculite where the smoke dome meets the chimney. It seems to be factory made and was made in a form have no previous experience with this brand