kingwinner Posted November 7, 2005 Report Share Posted November 7, 2005 "There are 4 things that must be satisfied for a substance to be a mineral:(i) natural(ii) inorganic(iii) solid in crystalline form(iv) definite chemical composition" I don't fully understand (iii) and (iv). 1) Gold is a naturally occurring inorganic substance that forms in the earth's crust. It is a solid and has a definite chemical composition. Is gold a mineral? Explain your answer. (Assume you know nothing about gold, as if it is an unknown substance that you have to determine if it is a mineral or not.) This is a question from my text book's section review. From the above information, gold seems to be missing something that must be satisfied to be a mineral, gold is a solid but is not mentioned to have crystalline form. For a mineral layman like me, I would predict that gold is not a mineral according to the information provided, right? For (iii) solid in crystalline form, is it true that a solid always has crystalline form, and a substance that has crystalline form is always a solid? If so, I would predict that gold is a mineral now since the information says that it is a solid, and this automatically satisfies the (iii) requirement. If not, gold is not a mineral...I think... 2) For the (iv) requirement for a mineral, "definite chemical composition", what does it mean by that? I don't get it! Is concrete a mineral and why? 3) Are rocks mixtures (not chemically united) or compounds (chemically united)? 4) An example of a mineral with a basic structure consisting of single tetrahedra linked by atoms of other elements is ________(pick one of mica, olivine, quartz, or feldaspar)I can't tell if the answer is mica or olivine, can someone explain? I don't understand! Can someone who know "minerals" explain? Thanks a lot! :friday: Turtle 1 Quote Link to comment Share on other sites More sharing options...
cwes99_03 Posted November 7, 2005 Report Share Posted November 7, 2005 A crystal is a solid, a solid is not necessarily a crystal. Hope that helps, but I won't answer the question for someone who should read and learn a little bit more (happy reading.) Quote Link to comment Share on other sites More sharing options...
LOC Posted November 7, 2005 Report Share Posted November 7, 2005 "There are 4 things that must be satisfied for a substance to be a mineral:(i) natural(ii) inorganic(iii) solid in crystalline form(iv) definite chemical composition" I don't fully understand (iii) and (iv). 1) Gold is a naturally occurring inorganic substance that forms in the earth's crust. It is a solid and has a definite chemical composition. Is gold a mineral? Explain your answer. (Assume you know nothing about gold, as if it is an unknown substance that you have to determine if it is a mineral or not.) This is a question from my text book's section review. From the above information, gold seems to be missing something that must be satisfied to be a mineral, gold is a solid but is not mentioned to have crystalline form. For a mineral layman like me, I would predict that gold is not a mineral according to the information provided, right?Gold does have a crystalline form, it is you just don't see it very often because gold is soft and often occurs as nuggets (which get rounded) or in veins with little or no open space. If gold precipitates in a void, it does display very nice crystalline structure. Click on THIS link from MinDat website for a close-up of crystalline gold - the crystals are beautiful and clearly isometric. Google "crystalline gold" and you will find many more images of what crystalline gold looks like. It's rare and often, crystalline gold is worth more to mineral collector's than it's price per ounce. For (iii) solid in crystalline form, is it true that a solid always has crystalline form, and a substance that has crystalline form is always a solid? If so, I would predict that gold is a mineral now since the information says that it is a solid, and this automatically satisfies the (iii) requirement. If not, gold is not a mineral...I think...It's not true that every solid has a crystalline form. Solids can also be amorphous, such as a volcanic glass like obsidian. There is no question gold is a mineral. 2) For the (iv) requirement for a mineral, "definite chemical composition", what does it mean by that? I don't get it! Is concrete a mineral and why?As you stated above, those 4 items must be satisfied before something is considered a mineral, so no, cement is not a mineral. 3) Are rocks mixtures (not chemically united) or compounds (chemically united)?I would say both. Some rocks are mixtures of minerals, while others are composed on only one mineral, such as carbonate, or some rocks are amorphous, such as obsidian, which sounds like a compound to me. AbE: Hmmmm... I just noticed the post above. :friday: Am I answering quiz questions or something? Tormod and Turtle 2 Quote Link to comment Share on other sites More sharing options...
cwes99_03 Posted November 7, 2005 Report Share Posted November 7, 2005 http://www.webelements.com/webelements/properties/text/definitions/crystal-structure.html Definition of crystalline structure. Read your book! Quote Link to comment Share on other sites More sharing options...
Turtle Posted November 7, 2005 Report Share Posted November 7, 2005 ___In all fairness to Kingwinner, he has read his book, & brings questions here when there is ambiguity in the book & other sources he has consulted to resolve those ambiguities muddy the waters even more. We -Hypography - are just such a source and a scolding by us isn't warranted.___I get the sense King is using every resource at his disposal to learn information he has a genuine interest in. :friday: Quote Link to comment Share on other sites More sharing options...
kingwinner Posted November 9, 2005 Author Report Share Posted November 9, 2005 ___In all fairness to Kingwinner, he has read his book, & brings questions here when there is ambiguity in the book & other sources he has consulted to resolve those ambiguities muddy the waters even more. We -Hypography - are just such a source and a scolding by us isn't warranted.___I get the sense King is using every resource at his disposal to learn information he has a genuine interest in. :friday:Thanks! You know me well! :friday: Quote Link to comment Share on other sites More sharing options...
HydrogenBond Posted November 9, 2005 Report Share Posted November 9, 2005 Minerials are usually composed of metals and nonmetals combined in a crystal structure. The most common are oxides. There are also minerials with sulfure, chloride, fluoride, etc.. This all imply ionic bonding. Gold is a nobel metal that is chemical resistant to almost all nonmetals so it not a mineral in the way defined because it doesn't easily form a ion state throughout. Quote Link to comment Share on other sites More sharing options...
LOC Posted November 9, 2005 Report Share Posted November 9, 2005 Minerials are usually composed of metals and nonmetals combined in a crystal structure. The most common are oxides. There are also minerials with sulfure, chloride, fluoride, etc.. This all imply ionic bonding. Gold is a nobel metal that is chemical resistant to almost all nonmetals so it not a mineral in the way defined because it doesn't easily form a ion state throughout.A mineral can be composed of one native element or several elements. What is most important is crystalline structure. Quote Link to comment Share on other sites More sharing options...
UncleAl Posted November 9, 2005 Report Share Posted November 9, 2005 4) http://www.mazepath.com/uncleal/sio2lat.gif Quote Link to comment Share on other sites More sharing options...
kingwinner Posted November 10, 2005 Author Report Share Posted November 10, 2005 1) Lets reword the question and put in this way:Substance X is a naturally occurring inorganic substance that forms in the earth's crust. It is a solid and has a definite chemical composition. Is Substance X a mineral? Would this be a mineral based on the given information? (no information about whether it has crystalline form or not...however we know that it is a solid, is that enough for it to be a mineral?) 2) Definite chemical composition means it can be representated by a chemical formula, I think! Does concrete have a definite chemical composition? 3) Are rocks homogeneous mixtures (solution) or heterogeneous mixtures? Quote Link to comment Share on other sites More sharing options...
LOC Posted November 10, 2005 Report Share Posted November 10, 2005 1) Lets reword the question and put in this way:Substance X is a naturally occurring inorganic substance that forms in the earth's crust. It is a solid and has a definite chemical composition. Is Substance X a mineral?Not necessarily. If it's lacking crystalline structure, then it would be more appropriate to call it a mineraloid. A mineral must have an orderly arranged internal structure (i.e., crystalline structure). Opal, limonite, mercury, and various others are mineraloids, each lack an orderly internal arrangement of atoms. In addition, mineraloids can have an organic component - amber and pearls are considered mineraloids. Would this be a mineral based on the given information? (no information about whether it has crystalline form or not...however we know that it is a solid, is that enough for it to be a mineral?)It can be mineral-like or a mineraloid, but it cannot be formally labeled a mineral unless it exhbits crystalline structure. 2) Definite chemical composition means it can be representated by a chemical formula, I think! Does concrete have a definite chemical composition?I'm not sure it does. It's composed of several individual compounds and it more similar to some rocks. 3) Are rocks homogeneous mixtures (solution) or heterogeneous mixtures?What do you mean by solution? Rocks can be both homogeneous and heterogeneous. Rocks composed of one mineral are homogeneous and rocks composed of more than one mineral are heterogeneous. Quote Link to comment Share on other sites More sharing options...
HydrogenBond Posted November 10, 2005 Report Share Posted November 10, 2005 Rocks are often composite of crystalites. The overall material may not be one crystal but will usually contain multitude of smaller crystals. One can crack open a rock and see them. Naturally occurring glass may form, these are not crystals but can still be silica. Natural deposits of copper, in Michigan, gold in alaska and silver in Nevada might also be considered mineral deposits. If one had the mineral rights on some land, that legal right might also include oil and coal. Quote Link to comment Share on other sites More sharing options...
kingwinner Posted November 11, 2005 Author Report Share Posted November 11, 2005 The terms "homogeneous mixtures" and "solution" have the same meaning. Can I ask another question? I quoted 2 paragraphs in my text: "Of the 20 rock-forming minerals, 10 are so common that they make up 90% of the mass of the earth's crust. These minerals are quartz, orthoclase, plagioclase, muscovite, biotite, calcite, dolomite, halite, gypsum, and ferromagnesian minerals, which include olivines, pyroxenes, and amphiboles" "Quartz and feldspars are common silicate minerals. Besides, there are ferromagnesian minerals rich in iron and magnesium. They include olivines, pyroxenes, amphiboles, and biotite." In paragrpah 1, ferromagnesian minerals include olivines, pyroxenes, and amphiboles. And "biotite" is a treated as out the the ferromagesian minerals, being treated separately as 1 of the 10 common rock-forming minerals. In paragraph 2, ferromagnesian minerals include 4 things: olivines, pyroxenes, amphiboles, and biotite. The "biotite" is brought in to the ferromagnesian minerals. Why is it like so? This is confusing...so should it be "Of the 20 rock-forming minerals, nine (instead of 10) are so common that they make up 90% of the mass of the earth's crust"? Quote Link to comment Share on other sites More sharing options...
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