What an interesting topic - well thought of, Annie. Strangely enough, I had to write an essay for my crystal course at the weekend and talk about crystals that I liked and why (well over 1,000 words, so will not replicate it here), also about those that I did not like and why. I shall share my thoughts here!!! It actually isn't that many that I really do not like, but my first one is the same as you mentioned, Annie:
Amethyst - I know this is a very popular crystal for many people but I have found that it has become “too” popular and people have chosen Amethyst more as a fad than for its properties. Having said that, when we had the shop, Amethyst was a stone that we sold regularly in answer to the properties below:
Amethyst is a crystal that helps with addictions and is often called the "sobriety stone". Amethyst brings energies in mystical realms of stability, peace, calm, balance, courage and inner strength. It is often used in metaphysics and crystal healing to protect against psychic attacks. On the spiritual level, amethyst is said to help open to communication with angels, telepathy and other psychic abilities. It is an excellent stone for meditation or dream work, past life work, and to help you see your path. Physically Amethyst is said by spiritual healers and mystical lore to heal the withdrawal symptoms of any sort of addiction, help with headaches, insomnia, arthritis, pain relief, circulatory system issues, endocrine system problems, chronic fatigue, fibromyalgia, immune system deficiencies and general healing. Amethyst is associated with the brow and the crown chakras.
Malachite - I just feel that the energies contained within Malachite are just too powerful for my comfort. However, it is a stone that I would choose to use, should the situation call for it, as below:
Malachite is a stone of transformation and helps with change and spiritual evolution. It can clear and activate all chakras, as well as balance them. Malachite is a stone that bridges the energy of the heart and root chakras. It helps balance pure love, romance and one's own well-being. Malachite is a stone of good fortune and prosperity/abundance. Malachite is also a very protective stone, being especially helpful for general protection, protection from evil, protection during pregnancy and childbirth and protection for children. It is also an excellent protection stone during flying and other travel. Using this stone, one can counteract self-destructive romantic tendencies and help encourage true, pure love. Malachite is also good for enhancing emotional stability and balance in general. It can decrease one's tendency to radiation illness, asthma, arthritis and tumours. Malachite is associated with the Heart Chakra.
Rose Quartz - Again, to my thinking, this crystal has become a very commercialised stone but it does have its uses and, if needed, I would select this stone, in response to the properties below:
Rose Quartz is a crystal of unconditional love. It activates the Heart Chakra to all forms of love – self, family, platonic and romantic. This crystal gives excellent protection during pregnancy and childbirth. Rose Quartz also brings forgiveness, tolerance and gentleness to situations. This crystal is also said to be helpful in the area of weight loss. Rose Quartz is associated with the Heart Chakra.