My mom passed

My mother passed away suddenly and it has been a whirlwind few days. The tribe helped me out a lot. My question is about ashes. We had her cremated and we were going to put a few into glass pendants. We were advised to not do that. I didn't know this but the belief is that is prolongs mourning and she needs to be returned to the earth. I am from the Gila river nation. I want to respect my culture and I haven't dealt with a native death before this. Has anyone heard of this before? I will respect it of course.