Tantra means union, or the harmonious mergence of energies. Tantric Twins share a common base and yet have two distinct terminations at the apex. Both terminations may or may not be the same height. Sometimes, where the single crystals meet, there will be brilliant fluorescent rainbows. These crystals relate to personal relationships and to the harmonious union of two separate, yet intimately bonded individuals. The ones with rainbows will transmit a sense of joy while replaying the many rays and ways that relationships can be coloured. The Tantric Twins transmit the reality of unity. By holding them, meditating with them, sleeping with them, or just having them around, greater unification starts to take place. In private use, they can bring one closer to the source, or when working with another person, create a closer connection. They can help to balance conflicting relationships, helping us to see that there are always solutions that can be found in resolving disagreements. According to Judy Hall, this Crystal can be programmed to attract a soul partner – a “Twin Flame”.  The Twinflame or Tantric Twin Crystal should be placed in the relationship corner of your home or your bedroom (this is the furthest right from the door).
 
The result is an intergrowth of two separate crystals in a variety of specific configurations. The surface along which the lattice points are shared in twinned crystals is called a composition surface or twin plane. Crystallographers classify twinned crystals by a number of twin laws.
 
TWIN CRYSTALS have two terminations (points) at the same end, which have developed from a single base. You can tell a twin crystal from two crystals that are simply attached to each other, by the fact that both parts of a twin crystal are exactly parallel to each other, and have no boundary between them in at least a small region of the crystal. These are wonderful crystals to use when dealing with `relationship' things. They can help you gain insight into the underlying problems in a relationship, and help work through them. They can generate very positive energy towards improving a relationship. This works for any kind of relationship, not only a man-woman relationship. A twin with a rainbow can be very effectively used to project healing energy into a relationship or to keep a good relationship strong.
When you are having a problem with a relationship sit quietly with the twin and ask for help. Remember, that answers come from many directions.
Twins are personal crystals as one of the twins is very closely tuned to your energy, so it is not possible to use this crystal to work for others in relationship matters.
 
Twin Quartz crystals can be recognized by the presence of two individual points, where the body of these two crystals are growing together from a common base.
There are specific variations in the quartz configurations of twin crystals. 
These include Tantric twins, where the two crystals are almost the same height, with the main body of both crystals growing parallel to each other.
Other types of twin crystals are twin soul or Gemini quartz, which grow from the same base rock, but they are clearly separate crystals that are growing side by side, yet almost equal in size and height. 
Any type of twin crystals are excellent to benefit relationships, as they help to create a better flow of emotional energy and balance between partners.
These crystals are not healing tools as such, but are used by you personally to heal your relationships, although they are useful crystals to benefit other types of relationships, such as that between members of a group, as they engender peace and harmony.