very well said, HIS and SLTR! grief is a necessary process and the crystals are only here to help us through that process in a more gentle and loving manner, not avoid it altogether.
I wish I had known about lithium quartz when I lost my baby at the end of last year. somehow this stone just completely escaped me. I think it is wonderful HIS that you were given knowledge of this stone in advance of your loss. So sorry to hear about your mother.
Since my loss process began, I have had a large rose quartz sphere and a piece of charoite next to my bed near my pillow. I suppose this combination is mimicking the effects of lithium quartz. It has definitely been a huge help. So keep in mind, sedgeez, that you can combine stones if you don't have certain things available or don't want to purchase more.
Hemera's suggestion of the auqamarines is interesting and, I feel, quite valid. I would say that I have been drawn to them since my miscarriage too. One caveat though, when you are still in the throes of grief, these can make you more weepy as they help you release your grief in a gentle sort of way. At least this is the effect they had on me.
As more suggestions, I would say that I have always found combining Rose Quartz with Rhodonite to be very effect when dealing with loss. (but again, more of a way of gently going through the grief, not avoiding it.) If you find Rose Quartz, or any stone, to be too strong for you, keep in mind that it is okay to only expose yourself to them in "limited doses".
On a related note, I also had a lot of hormonal problems (on going) since then due to the sudden drop in estrogen and other pregnancy hormones. Please consider consulting with a good herbalist to balance your hormones naturally and safely as this will really help with the emotional roller coaster. I have found a combination of Vitex compound and Dong quai to work wonders, however, your age and situation may call for something different. If you need something for that, a really good stone for hormone balancing is Turquoise.
(((((((((((sedgeez))))))))))) we are all here for you and keeping you in our thoughts and prayers. I wish I could do more for you but hopefully just knowing you are not alone in this will be of some comfort to you.