Natural Stone Supplies : Material Information : Black Galaxy & Star Galaxy Granite
  • Black Galaxy granite is one of the world's most popular granite choices however this very success is now creating a problem, consequently, and it does not matter whether you are a trade or retail buyer, it is important to understand the fundamental differences between the various qualities you may be offered.

    It is estimated that in excess of one million cubic metres of the granite has been quarried since extraction started.

    The technical geological name for this granite is Gabbric Anorthosite. The material has a hardness of around 4.5 on the Moh's scale which can be termed as moderately hard.

    Black Galaxy is from near Ongole, Andhra Pradesh, India. The original Galaxy material introduced in the early 1980's, with the densest black background and bright reflectors, is known as Star Galaxy. The Star Galaxy quarry is not a massive one therefore the volume of blocks produced could not supply all the dealers who purport to sell this material.

    The gold specks are due to the presence of ferrous rich Enstatine (Bronzite). Black Galaxy can be broadly divided into three types based on the size of the gold coloured specks as:

  • 1. Large specked Black Galaxy
  • 2. Medium specked Black Galaxy
  • 3. Small specked Black Galaxy
  • Like all natural stones Black Galaxy can and does vary in appearance and physical structure with natural veins a common feature within the material. Once again, these can broadly be divided into four types as follows:

  • 1. Slabs and tiles clean of any veining
  • 2. Slabs and tiles with one vein line
  • 3. Slabs and tiles with two vein lines
  • 4. Slabs and tiles with three vein lines or more
  • It must be stated that the vein lines do not affect the integrity of the material. They are natural hence they cannot be removed.

    The presence of natural veins exists in nearly all the quarries, and considering that the recovery rate of the material has been poor, this has pushed up the cost of quarrying quite considerably. However the past few years has seen the Chinese purchasing many of the smaller blocks, many with veining, since they are not so obssessed with the Western culture of a "perfect" natural material. The Chinese now account for 95% of the purchases of small blocks.

    Some blocks when viewed closley actually have a green tinge and slightly open veining in the background. Once more this does not affect the integrity of the material however this quality is usually valued slightly less and this quality particularly may need sealing when used for kitchen counter tops.

  • SURFACE PITTING: Added 21st May 2007
  • All Black Galaxy has natural surface pitting owing to its petrographical composition and even after resining of the material small pits and natural fissures may be evident. It is generally accepted that the the deeper in the quarry the blocks are extracted, say 10-20 metres below ground level, that more pitting is found to exist in the blocks. Generally those quarries above ground level, 50-70 metres, have less pitting in the processed slabs.

    This is a totally natural occurence and if one's preference is for an absolutely perfectly smooth, gloss finish with no natually evident features, then selection of this material is not recommended.

    It is thought that the pitting is not caused by the Bronzite specks but by sand/mud holes formed when the magma flowed across the land and cooled down. The pits are generally very smooth and it is extremely difficult for resin to attach itself to the surface.

    Taking all the above information into account, it is clear that for large contracts a considerable saving may be made by using pre-dimensioned materials with an acceptable colour and variable veining.

  • Update February 2005
  • There are now over 44 quarries spread over 400 acres of land. The sizes of quarries range between 2 and 20 acres each. Around 8,000 CBM (Cubic Metres) of Black Galaxy granite is produced every month. Only 40% of the volume make up big blocks and are commonly called gang-saw size blocks and these are blocks of sizes above 2.40m x 1.20m x 1.00m.

    The remainder of the blocks are used for producing tiles, dimensioned slabs, vanity units etc.

    Precisely because of the variation of block sizes, in colour quality and vein lining, the price of the raw Galaxy rough blocks from the quarry can have an enormous price variance. The price paid for the rough block will be reflected in the finished product and since Black Galaxy is actively traded as a commodity and owing to the large volume of quarrying, large blocks in First Choice material are becoming scarcer and much more expensive.

    As with all natural materials it is very important to view Black Galaxy before buying and not to buy on price alone.

  • New Grading Standards
  • Taking into account all the above information we have decided to introduce our own grading standard for the qualities we shall supply so that the client may select their most preferred material, these will be:

  • 1. Black Galaxy Q1 : No veining or one single vein
  • 2. Black Galaxy Q2 : One or two veins
  • 3. Black Galaxy Q3 : Two, three or more veins
  • Non-acceptance of these conditions will mean we cannot supply.

    Black Galaxy & Star Galaxy Granite : Technical Specifications
    Description of Black Galaxy, Star Galaxy This material has a dark black background with golden specks in it.
    General Usage for Black Galaxy, Star Galaxy It is mainly used for flooring, cladding, kitchen counters and table tops. It looks best when it is glossy. Available in both slabs and tiles.
    Quarrying Area for Black Galaxy, Star Galaxy Cheemakurti, Bodawada, Prakasam District, Andhra Pradesh, Southern India
    Technical Specification  
    Compressive Strength 2777 Kg/cm2
    Comp.  Strength after Gelivity 2696 Kg/cm2
    Ultimate Tensile Strength 274 Kg/cm2
    Coeff. Thermal expansion 0.0045mm/mcº
    Water Absorption 0.04%
    Impact Test-Min Fall Height 68 cm
    Specific Gravity 2.960 Kg/m3
    Hardness (Moh's Scale)   6.5
    These figures and details are given for guidance purposes only, no reliance should be taken as to their accuracy.

    Natural Stone Supplies : Material Information : Black Galaxy & Star Galaxy Granite

    If you wish to add or amend any information about Black Galaxy please e-mail us here.

    To learn more about general rock composition and mineralogy please click here.

    As always "Caveat Emptor - Buyer Beware!"

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