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Updated: June 12, 2025
That is calcite, and this rock is a black limestone; all the indications are, therefore, in favour of this being a genuine emerald mine, which we can work, if we choose, on our return journey.
The Glacier flows between two high walls of dark rock, and the steep incline of perhaps seventy feet, covered with a smooth deposit of calcite and shining with moisture, has the appearance of ice and is as uninviting for a climb. The top is connected with the roof above by a group of short, and for this region, heavy columns of dripstone, the oldest formation of that character in the cave.
In shells originally made of ARAGONITE, a crystalline form of carbonate of lime, that mineral is usually replaced by CALCITE, a more stable form of the same substance. The most common petrifying materials are calcite, silica, and pyrite. Often the organic substance has neither been preserved nor replaced, but the FORM has been retained by means of molds and casts.
An occasional overflow of the lake passes out to one side, then turns and goes under the Glacier where its first few feet of descent are called the Pearl Beds, where a variety of water-polished pebbles are being coated over and cemented together with calcite crystal.
Hillebrand and Norton, in Bunsen's laboratory. Cerium looks like iron, having both its color and lustre, but is heavier, and has the hardness of calcite. It tarnishes slowly in dry air and rapidly in moist air. It ignites so readily that pieces scratched off inflame, and its wire burns more brilliantly than magnesium wire. Lauthanum is a little harder, but also a little lighter.
In South Australia reef gold is almost invariably associated with iron, either as oxide, as "gossan;" or ferruginous calcite, "limonite;" or granular silica, conglomerated by iron, the "ironstone" which forms the capping or outcrop of many of our reefs, and which is often rich in gold.
Flooded with the brilliant white light of magnesium ribbon, the crevice walls could be seen drawing together at a height of sixty-five feet, and both composed entirely of larger box work than any seen before and very heavily covered with calcite crystal, colored a bright electric blue and glowing with a pearly lustre.
The Catacombs are a series of connected fissures and small crevices in which every inch of exposed surface is covered with clear, translucent, almost transparent, calcite crystals, neither coated with lime nor stained with clay; nor even is the pearly lustre dimmed with the slightest trace of dust.
The veins of it are difficult to distinguish from the calcite, as they are almost identical in color, and many of the calcite veins are partly of pectolite in fact, every third or fourth vein will contain more or less of it.
The geode taken proved on opening to be especially fine, being filled with pearly white calcite crystals of both the dog-tooth and nail-head forms, and was kindly presented to be added to the collection of cave specimens already purchased in town, to which were also added handsome pieces of "drusy" quartz, cave coral, and tufa and mineral wool.
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