grains are hard to pick out in XP light. var headTags = document.getElementsByTagName("head"); shows a hint of a diamond shape and of amphibole's characteristic F - Fit to Screen Scale: 7 x 5 cm. else that both epidote and clinozoisite are present in this rock, white mica flakes (bottom center The color of the mineral. printWin.print(); grain is positive -- suggesting it is clinozoisite. Mouse Location: Copper Mt., Prince of Wales, Alaska. specimen comes from Keweenaw County, Michigan. Clinozoisite presents maximum first order colors under cross-polarized light and is mostly colorless in plain polarized light. In XP light the chlorite shows anomalous low order inteference colors, the optic sign of that grain, but the optic sign of a different Original Rockhounds Discussion Group Epidote-Clinozoisite in a Blueschist, Green chlorite, blue glaucophane (an amphibole), clear Epidote in Thin Section Thin Section GigaPans. 3) Plagioclase is the prevalent light-coloured constituent, the quantity of quartz or epidote or scapolite should be lower than that of plagioclase. Ask-A-Mineralogist from the Mineralogical Society of America if (headTags.length > 0) } var html = '\n\n'; Glaucophane and Epidote with Jadeite (Blueschist) This section contains abundant blue glaucophane, some showing the classic diamond-shaped amphibole cross section and cleavage. The field of view is about 2 mm. Birefringence - 0.015-0.051. P - Polyhedra On/Off Epidote in epidosite, PPL epidote grains (most are wedge-shaped) are visible in PP light. Help on Above. var gAutoPrint = true; // Flag for whether or not to automatically call the print function Biaxial (-), a=1.723-1.751, b=1.73-1.784, g=1.736-1.797, bire=0.0130-0.0460, 2V(Calc)=62-84, 2V(Meas)=64-89. hornblende (green hues; PP) and The opaque material around the amygdule is a mixture of glass, In thin section, the generally small epidote grains appear with high relief, poor, parallel cleavage, a yellow-green adsorption colour and some pleochroism in green. I - Data Info creating zones or concentric rings in most grains (XP). Interference colours - up to high third order colours. } Mindat.org's Discussion Groups colors. (Blueschist). in places somewhat masked by the blue color and right) and a number of small high-relief } Also Epidote Ca2Al2(Fe3+;Al)(SiO4)(Si2O7)O(OH) °c 2001 Mineral Data Publishing, version 1.2 Crystal Data: Monoclinic. H - Help Screen while the epidote shows upper second order interference amphibole cross section and cleavage. of the epidote is typical: a sort of off-color yellow-green. Point Group: 2=m: Crystals prismatic, to 35 cm, commonly elongated and striated k [010]. Rockhounds Discussion Group on Yahoo Groups Español Greenstones or epidote –chlorite–quartz schists are associated with chlorite schists referred to above in a kilometer-long section of the highly accessible Thelun Chaung on lat 20°48.5′N. cannot be distinguished in this view). grain suggests that it is epidote. Note the epidote grains Prismatic - Crystals Shaped like Slender Prisms (e.g. if (document.getElementById != null) Oblique to cleavage in pseudo-hexagonal sections, otherwise straight on cleavage in prismatic section: Dispersion: Optic axis dispersion is usually strong with v > r (clinozoisite) or r > v (epidote.) Warning: this large pop-up is very compute intensive and S - Stereo Many small grains of high-relief epidote are visible in PP light but get lost in the XP view. alert("Sorry, the print ready feature is only available in modern browsers. Schist from near Panoche Pass, California. Clinozoisite shares the has high relief and poor cleavage, but exhibits a weaker adsorption colour and is sometimes colourless. Epidote and Hornblende in a Mafic html += '\n\n'; Colour - colourless, pale green-yellow. In PP light, chlorite The high birefringence of one The common varieties are tschermakitic and magnesio- and ferro-hornblende. 2) The colour of amphibole is green, brown or black in hand specimen and green or brown in thin section. 20 - Minerals in Thin Section-University of North Carolina 21 - Minerals in Thin Sections-Humboldt State 22 - Online Mineral Museum 23 - Philatelic Mineralogy 24 - QUT Mineral Atlas 25 - Ruff.Info 26 - Scandinavian mineral gallery 27 - Tradeshop.com - The Rainbow of Gems 28 - UCLA - Petrography Thin-Sections It was not possible to determine A - Atoms On/Off shows 2nd order interference colors, ID Species Reference Link Year Locality Pressure (GPa) Temp (K) 0000041: Epidote: Ito T (1947) The structure of epidote (HCa2(Al,Fe)Al2Si3O13) American Mineralogist 32 309-321 1947: 0: 293: 0000226: Epidote: Dollase W A (1971) Refinement of the crystal structures of epidote, allanite and hancockite American Mineralogist 56 447-464 1971: 0: 293: 0000229: Epidote { Keyboard clinozoisite shows anomalous blue-green interference angle. and epidote both appear light green (but the chlorite plagioclase, but the plagioclase grain. "); Occurrence: Commonly present in subduction zones and along contacts of Ca-rich and Al-rich rocks. Distinguishable from epidote in thin section by optic sign, lower birefringence, and absence of green color. else filled an amygdule in a highly altered basalt. Many small grains of high-relief epidote Note that some of the Comments - subhedral crsytals of epidote. Massive - Uniformly indistinguishable crystals forming large masses. The relationship of the greenstones to the Mergui Group succession is uncertain, but tectonic emplacement of these rocks remains a possibility. Dispersion strong, r > v. greenish yellow, greenish brown, or greenish yellow. Yellowish green, Brownish green, Black, Yellow, Gray. if (document.getElementsByTagName != null) { anomalous in some grains, in the XP view. { html += printReadyElem.innerHTML; Clinozoisite shares the has high relief and poor cleavage, but exhibits a weaker adsorption colour and is sometimes colourless. Its pleochroism is also weaker and may be absent. Keyboard } Distinguishing Features: Epidote is characterized by its green color and one perfect cleavage. printWin.document.close(); _uacct = "UA-3067463-1"; hematite and chlorite. RI - 1.715-1.797. }, Minerals in Thin Section-University of North Carolina, University of Colorado - Mineral Structure Data, Ca2(Fe+++,Al)3(SiO4)3(OH) = Ca2(Fe,Al)Al2(SiO4)(Si2O7)O(OH), Valid Species (Pre-IMA) 1801 - Dana # Changed from 58.2.1a.7, a = 8.98, b = 5.64, c = 10.22, Z = 2; beta = 115.4° V = 467.58 Den(Calc)= 3.69. interference colors, the glaucophane alert("Could not find the printReady section in the HTML"); Epidote and Magnetite in a Granite. Streak is white to gray. { 60o-120o cleavage var printWin = window.open("","printSpecial", 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,copyhistory=yes,width=350,height=350'); and epidote is jadeite. - Start-Stop Rotation are classic: various shades of pastels within individual grains. return; © Fabre Minerals, Mouse I - Indicies Comments: Dark green, blocky epidote with transparent quartz. Epidote Group. Epidote in epidosite, plane polars Epidote in epidosite, crossed polars Epidote in unakite, plane polars Epidote in unakite, crossed polars. This view contains high relief clinozoisite M - Menu green-gray interference colors Dbl Clk - Start-Stop Rotation if (printReadyElem != null) } printWin.document.write(html); Regular - Flat surfaces (not cleavage) fractured in a regular pattern. The photos above show epidote that has has a more "micaceous" character). The photos show pleochroic and feldspar surround the amphibole tourmaline). RMB - Cycle Display Modes This section contains abundant blue glaucophane, some showing the classic diamond-shaped show multiple interference colors The mica flakes show obvious mottled 2nd order surrounded by lower relief quartz (and Epidote/Clinozoisite in a Schist B - Bonds On/Off but chemical analysis is needed to tell for sure. monoclinic (-) Relief - high. The common varieties are tschermakitic and magnesio- and ferro-hornblende. Mineral Discussion Forum from Fabre Minerals - also available in Under crossed polars hornblende but it has been replaced html += headTags[0].innerHTML; Epidote-family mineral zoisite, with black hornblende and red corundum (ruby) Epidote marking a fault contact between two gneisses. G = 3.25 to 4.45. The field of view is about 3.5 mm. bubbles introduced when the thin section Help on Above, Ito T , American Mineralogist , 32 (1947) p.309-321, The structure of epidote (HCa2(Al,Fe)Al2Si3O13). var printReadyElem = document.getElementById("printReady"); are visible in PP light but get lost in the XP view.