Intermediate Species

The possible admixtures among the garnet group species give rise to the following intermediate species which are known in the trade as Rhodolite, Malaya, Pyrandine, Pyralspite, etc. As there are varying percentages of isomorphous replacements, their properties show considerable variations.

Pyrope – Almandine Garnet (Rhodolite): Color is basically purplish red, brownish red and violet-red, whose properties are as follows:

S.No. Particulars Properties
1. Refractive Index 1.75 – 1.78
2. Specific Gravity 3.80 – 3.95
3. Spectrum Main diagnostic strong bands at 505nm, 527nm and 575nm
4. Magnification Silk (intersecting rutile needles at 70° / 110°), crystalline inclusions (apatite, zircon, spinel, etc.), fluid inclusions

 

Pyralspite with Grossular Garnet (Malaya): Color is basically orange-brown-red and the properties are as follows:

S.No. Particulars Properties
1. Refractive Index 1.76 – 1.81
2. Specific Gravity 3.70 – 4.25
3. Spectrum Bands may be seen at 505nm, 527nm and 575nm, along with lines of Mn at 432nm and 412nm.
4. Magnification Liquid inclusions, rounded crystals, etc.

 

Pyrope – Spessartite Garnet (Color Changing): The color is bluish green in daylight and purplish red in lamplight. Some exhibit a purplish blue to purplish red color change.

S.No. Particulars Properties
1. Refractive Index 1.75 – 1.81
2. Specific Gravity 3.60 – 4.10
3. Spectrum Bands may be seen at 505nm and 575nm, along with lines at 485nm, 465nm and 435nm. A cutoff is seen at 435nm.
4. Magnification Liquid fingerprints, 3 directional long needles, crystals, etc.

 

Grossular – Andradite Garnet (Grandite): The color is basically greenish yellow and brownish green.

S.No. Particulars Properties
1. Refractive Index 1.75 – 1.81
2. Specific Gravity 3.60 – 3.70
3. Spectrum Bands may be seen at 440nm and 445nm along with lines at 495nm and 600nm.
4. Magnification Highly reflecting fingerprints, growth zoning, crystals, etc.

 

Reader Interactions

Leave a Reply