This is not the traditional twin crystal. These two points have truly merged into one. I consider this one the twin flame 5D total union. I might have just made up a new crystal catigory. It's beautiful. 
 
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.
 
RAINBOW CRYSTALS have a rainbow reflected from within the crystal. Usually they are best viewed in sunlight. These crystals are especially good as meditation crystals for working deep within the subconscious. They work particularly well to lighten the mood for people experiencing sadness, grief or depression. Just holding a rainbow crystal can lighten your mood. Rainbow crystals are also very good at drawing negativity from a room or a situation. Always cleanse a crystal that has been used to clear negativity by letting it sit in the sunshine for a while.
Exercise: Rainbow crystals bring joy into your life. If you are sad or depressed sit and meditate on the rainbow. It can help lighten your mood. If working with another, let him hold the crystal if he is with you. If he is not with you, hold the rainbow and visualize white light leaving the rainbow and going to him.