for other uses of petrifaction, see petrified disambiguation . perseus turning king polydectes to stone with the head of medusa. petrifaction, or petrification as defined as turning people to stone, is a common theme in folklore and mythology, as well as in some works of modern literature. petrification is associated with the legends of medusa .
the composition of a sandstone can have important information regarding the genesis of the sediment when used with a triangular quartz, feldspar, lithic fragment qfl diagrams . many geologists, however, do not agree on how to separate the triangle parts into the single components so that the framework grains can be plotted.
then, as the bronze cools, it shrinks a little, making it easier to separate from the mould. their strength and ductility lack of brittleness is an advantage when figures in action are to be created, especially when compared to various ceramic or stone materials such as marble sculpture .
pieces of lodestone, suspended so they could turn, were the first magnetic compasses, and their importance to early navigation is indicated by the name lodestone, which in middle english means 'course stone' or 'leading stone', from the now-obsolete meaning of lode as 'journey, way'.
many members of the church of jesus christ of latter-day saints believe that joseph smith used this seer stone in the book of mormon translation effort. according to latter day saint theology, seer stones were believed to have been used by joseph smith, as well as ancient prophets, to receive revelations from god.
the process of mining from discovery of an ore body through extraction of minerals and finally to returning the land to its natural state consists of several distinct steps. the first is discovery of the ore body, which is carried out through prospecting or exploration to find and then define the extent,.
gemmology. ruby and pink sapphire are the red and pink varieties of the mineral corundum, an aluminum-oxide mineral al2o3.the pink/red colour is formed in corundum by adding the element chromium to its crystal structure. spectroscopy of rubies from the aappaluttoq occurrence in greenland confirm the presence of chromium as well as showing absorption in the uv region indicating high fe iron .
meadows of gold and mines of gems arabic: مُرُوج ٱلذَّهَب وَمَعَادِن ٱلْجَوْهَر , murūj aḏ-ḏahab wa-maʿādin al-jawhar is an historical account in arabic of the beginning of the world starting with adam and eve up to and through the late abbasid caliphate by medieval baghdadi historian al-masudi arabic: ٱلْمَسْعُودِيّ .
the minerals have to be crushed, roasted and smelted to concentrate the metallic components in order to separate the noble metals. by the renaissance the use of the cupellation processes was diverse: assay of ores from the mines, testing the amount of silver in jewels or coins or for experimental purposes.
a diamond with facets cut only a few degrees out of alignment can result in a poorly performing stone. for a round brilliant cut, there is a balance between 'brilliance' and 'fire'. when a diamond is cut for too much 'fire', it looks like a cubic zirconia, which gives off much more 'fire' than real diamond. a well-executed round brilliant cut .
heavy liquids such as tetrabromoethane can be used to separate ores from supporting rocks by preferential flotation. the rocks are crushed, and while sand, limestone , dolomite , and other types of rock material will float on tbe, ores such as sphalerite , galena and pyrite will sink.
a mesh strainer, also known as sift, commonly known as sieve, is a device for separating wanted elements from unwanted material or for characterizing the particle size distribution of a sample, typically using a woven screen such as a mesh or net or metal. the word 'sift' derives from 'sieve'. in cooking, a sifter is used to separate and break .
while native gold is common, the ore will sometimes contain small amounts of silver and copper. the romans utilised a sophisticated system to separate these precious metals. the use of cupellation, a process developed before the rise of rome, would extract copper from gold and silver, or an alloy called electrum.
adder stone was held in high esteem amongst the druids. it was one of their distinguishing badges, and was accounted to possess the most extraordinary virtues. there is a passage in pliny’s natural history, book xxii, describing the nature and the properties of this amulet. the following is a translation of it:
goldstone is a type of glittering glass made in a low-oxygen reducing atmosphere. the finished product can take a smooth polish and be carved into beads , figurines , or other artifacts suitable for semiprecious stone, and in fact goldstone is often mistaken for or misrepresented as a natural material.
a touchstone is a small tablet of dark stone such as fieldstone, slate, or lydite, used for assaying precious metal alloys. it has a finely grained surface on which soft metals leave a visible trace. the touchstone was used during the harappah period of the indus valley civilization ca. 2600–1900 bc for testing the purity of soft metals. it .