Tourmaline naturally results in a wide range of colours and even colour variations in the same gem in concentric or horizontal bands. The noteworthy colours found in Sri Lanka are yellowish green, dull green, honey yellow brown and rarely blue and bright green. The yellowish brown tourmalines are more abundant in Sri Lanka compared to other colour varieties. Attractive pink, bi-colour and Paraiba tourmalines are not found in Sri Lanka. The different colours could be seen along the length of the crystal and here the colours are at the two ends where the colour demarcations are very sharp.
Basic scientific details of tourmaline family are mentioned below.
The red and reddish varieties are identified as rubellite and in instances where the shade of red carries a purplish tint, these are identified as siberite. These varieties are not known to occur in Sri Lanka. Sri Lankan green products have always been of a dull green. These are more yellowish green in appearance. Most of the brown and yellowish brown varieties are located mainly around Uva, Rathnapura and Tissamaharama regions. The brown, brownish yellow and the honey yellow colour varieties are broadly identified as uvaite and dravite respectively. Uvaite has been named after the province of Uva where these varieties are most abundant and widespread. The other areas in which tourmalines are found widespread and in fair abundance are the Lunugala, Bibile, Passara, Nilgala region, Horana, Matugama, Pelawatte, Morawaka, Deniyaya, Rakwana areas, around Rathnapura, Avissawella, Haputale and also around Ambalantota in the south.
Basic scientific details of tourmaline family are mentioned below.
- Chemical Composition - Complex borosilicate of Aluminium, Magnesium and Iron
- Crystal System - Trigonal
- Hardness – 7.0 - 7.5
- Specific Gravity – 3.01 – 3.11 (black 3.15 - 3.26)
- Refractive Index – 1.62 – 1.66
The red and reddish varieties are identified as rubellite and in instances where the shade of red carries a purplish tint, these are identified as siberite. These varieties are not known to occur in Sri Lanka. Sri Lankan green products have always been of a dull green. These are more yellowish green in appearance. Most of the brown and yellowish brown varieties are located mainly around Uva, Rathnapura and Tissamaharama regions. The brown, brownish yellow and the honey yellow colour varieties are broadly identified as uvaite and dravite respectively. Uvaite has been named after the province of Uva where these varieties are most abundant and widespread. The other areas in which tourmalines are found widespread and in fair abundance are the Lunugala, Bibile, Passara, Nilgala region, Horana, Matugama, Pelawatte, Morawaka, Deniyaya, Rakwana areas, around Rathnapura, Avissawella, Haputale and also around Ambalantota in the south.