The close-up view of each stone type shows a relatively true image of the crystalline structure and the colouring. This is suitable for grained slabs to a limited extend only. In regard to the colour matching, please take an original sample of the stone from your furniture store as a basis.
Mineral content as in gabbro or basalt, namely:
50% colourless or, at most, dark grey transparent feldspar in randomly organised, prismatic crystals about 1 mm in size and dominated in colour by 30% of hypersthene and bronzite, both of which are deep black, together with 8% of metallically glittering flakes of ilmenite. There are traces of zirconium, apatite, olivine and various ores. The black mineral fractions are sometimes compacted into clusters or cloud-like.
Magma, originating from the earth's mantle, from depths of 50 km and more, intruded into cracks in the submarine crust and crystallised. While the cooling was slower than for extrusive volcanic rocks, it took place relatively fast for an intrusive rock. While structurally closer to the latter, such hypabyssal basalts, the volcanic equivalent of gabbro, have been given the special name of dolerite. The rock, formed 100th of millions years ago, was only later lifted and exposed by later folding and erosion.
|Structure Type||Homogeneous Structure|
|Synonyms||Volcano Black, Vulcano Black|
|Group||Plutonic rock - Plutonite|
|Petrographic Assignment||Granite - Dolerite (vulcanite)|
|Age||200-300 million years (Carboniferous)|
|Colouring Minerals||Dark-grey feldspar, black hypersthene and broncite, metallic-shining flakes of ilmenite|
|Average Hardness||7 (according to Mohs's hardness scale 1-10) / Natural stone|
|Deposit||Chennai - India|