Ferro-hornblende mineral data, information about Ferro-hornblende, its properties and worldwide locations. Pargasite occurs in high-grade metamorphic rocks that tend to have more aluminum. Our editors will review what you’ve submitted and determine whether to revise the article. Omissions? The four end-members and the cation content of their respective compositions are as follows: hornblende, Ca2(Mg4Al) (Si7Al); tschermakite, Ca2(Mg3Al2)(Si6Al2); edenite, NaCa2(Mg)5(Si7Al); pargasite, NaCa2 (Mg4Al)(Si6Al2). Defined as an amphibole in the magnesio-hornblende group of the Calcium subgroup with Fe 2+ >Mg and Al>Fe 3+ in the C position and (OH) as the dominant ion in the W position. Extensive solid solution occurs, and each end-member has iron-rich equivalents; minor elements, including manganese, titanium, chromium, potassium, fluorine, and yttrium, are usually present. Some members have potassium, titanium, and fluoride. Answer. Let us know if you have suggestions to improve this article (requires login). Other minerals in the hornblende series include: The word hornblende is derived from the German horn and blenden, to 'deceive' in allusion to its similarity in appearance to metal-bearing ore minerals. Top Answer. Formula: Ca 2 (Fe 2+ 4 Al)(Si 7 Al)O 22 (OH) 2. Hornblende is a complex inosilicate series of minerals (ferrohornblende – magnesiohornblende). Victoria Co. ⓘ McMillan Brook; Chatterjee, A.K. Hornblende occurs widely in metamorphic and igneous rocks. Hornblendes exhibit typical amphibole structures; these are based on double tetrahedral chains between which four metal sites are located. Hornblende’s generalized chemical formula is (Ca,Na) 2 (Mg,Fe,Al) 5 (Al,Si) 8 O 22 (OH) 2. A rare variety of hornblende contains less than 5% of iron oxide, is gray to white in color, and is named edenite from its locality in Edenville, Orange County, New York. Hornblende, calcium-rich amphibole mineral that is monoclinic in crystal structure. It is most often confused with various pyroxene minerals and biotite mica, which are black and can be found in granite and in charnockite. Many zones or isograds subdividing the facies have been recognized, and classic studies have been made in the Highlands of Scotland, New Hampshire and Vermont in the…. A generalized composition for the hornblende group is shown below. Connection: Linkedin, Video: Youtube, Research: Researchgate, Work: UAB, Twitter: docfossil The general formula is (Ca,Na)2-3(Mg,Fe,Al)5(Al,Si)8O22(OH,F)2. 1. Metamorphic rocks with abundant hornblende are called amphibolites. [Ferro-hornblende] Kontak, D.J. Hurlbut, Cornelius S.; Klein, Cornelis, 1985, This page was last edited on 17 November 2020, at 21:05. Very dark brown to black hornblendes that contain titanium are ordinarily called basaltic hornblende, from the fact that they are usually a constituent of basalt and related rocks. Hornblende alters easily to chlorite and epidote. The four end-members and the cation content of their respective compositions are as follows: hornblende, Ca 2 (Mg 4 Al) (Si 7 Al); tschermakite, Ca 2 (Mg 3 Al 2 ) (Si 6 Al 2 ); edenite, NaCa 2 (Mg) 5 (Si 7 Al); pargasite, NaCa 2 (Mg 4 Al) … 3 4 5. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Corrections? Updates? It is most often confused with various pyroxene minerals and biotite mica, which are black and can be found in granite and in charnockite. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. These minerals cannot be distinguished from one another without laboratory analysis. Tetrahedral substitution of aluminum for silicon is common and provides charge balance for trivalent and univalent substitution in the metal sites. Black Friday Sale! Variable Formula Wiki User Answered . This article was most recently revised and updated by, https://www.britannica.com/science/hornblende, The University of North Dakota - Hornblende-Actinolite, Amethyst Galleries' Mineral Gallery - The Mineral Hornblende. Hornblende has a hardness of 5–6, a specific gravity of 2.9–3.4 and is typically an opaque green, greenish-brown, brown or black color. Hornblende’s generalized chemical formula is (Ca,Na)2(Mg,Fe,Al)5(Al,Si)8O22 (OH)2. 2009-04-07 12:01:33 2009-04-07 12:01:33 (Ca,Na)2-3(Mg,Fe,Al)5Si8022(OH)2. Canadian Mineralogist: 31: 471-522. Hornblende has a hardness of 5–6, a specific gravity of 2.9–3.4 and is typically an opaque green, greenish-brown, brown or black color. Chemical Formula: Ca2[Mg4(Al,Fe+++)]Si7AlO22(OH)2 : Composition: Molecular Weight = 821.16 gm Calcium 9.76 % Ca 13.66 % CaO Magnesium 11.84 % Mg 19.63 % MgO Aluminum 5.75 % Al 10.86 % Al 2 O 3 Iron 1.70 % Fe 2.43 % Fe 2 O 3 Silicon 23.94 % Si 51.22 % SiO 2 Hydrogen 0.25 % H 2.19 % H 2 O Oxygen 46.76 % O _____ _____ 100.00 % 100.00 % = TOTAL OXIDE: Empirical Formula: Ca 2 Mg 4 Al … Chemical Formula: General Formula: Ca 2 (Mg,Fe 2+,Fe 3+,Al) 5 (Si,Al) 8 O 22 (OH) 2 Magnesio-hornblende: Ca 2 Mg 3,(Al,Fe)Si 7 AlO 22 (OH) 2 Ferro-hornblende: Ca 2 Fe 2+ 4,(Al,Fe)Si 7 AlO 22 (OH) 2: Composition: Complex basic silicate of sodium, calcium, magnesium, and aluminum. For detailed physical properties of hornblende, see amphibole (table). (Contact Scott Brande) mailto:email@example.com. Hornblende includes following series: magnesiohornblende-ferrohornblende, tschermakite-ferrotschermakite, edenite-ferroedenite, pargasite-ferropargasite, and magnesiohastingsite-hastingsite.
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