crystal is any naturally occurring inorganic crystalline substance with a fairly definite chemical composition.
crystal is any naturally occurring inorganic crystalline substance with a fairly definite chemical composition.
any naturally occurring inorganic crystalline substance with a fairly definite chemical composition?
crystal
iddingsite is a mineral that lacks a definite chemical composition, so exact compositions cannot be calculated. an approximated composition for a hypothetical end product of iddingsite has been calculated as being sio = 16%, alo = 8%, feo = 62% and ho = 14%. throughout the alteration process of olivine, there is a decrease in sio, feo and mgo and an increase in alo and ho. the chemical process associated with the alteration consists of the addition of feo and the removal of mgo (gay and le maitre 1961). the chemical formula for iddingsite is approximated as mgo * feo * 4 ho where mgo can be substituted by cao by a ratio of 1:4. there are also some trace constituents of nao and ko that enter iddingsite as the alteration process progresses.
iddingsite
a chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook. according to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. but, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties. the chemical substance index published by cas also includes several alloys of uncertain composition. non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".
chemical substance