Feldspar – Wikipedia, The Free Encyclopedia
White: Diaphaneity: opaque: Specific gravity: 2.55 – 2.76: Birefringence: first order: Pleochroism: none: Other characteristics: exsolution lamellae common … Read Article
Uniaxialminerals (
You will get best results by locating a grain showing the lowest birefringence, i.e., one in which the optic axis is near-vertical. 2. If the figure is off-center, make sure you know which quadrant you are dealing with. 3. Insert the gypsum compensating plate (530 nm) and observe the color change in the … View Document
PowerPoint Presentation
Insert gypsum accessory plate; Note color in NE, immediately adjacent to isogyre — Back to birefringence/interference colors . Observation: frequency of light remains unchanged during splitting, regardless of material … Access Doc
Optical Mineralogy
The full wave plate is also called a gypsum plate, 1l plate, 550 nm plate, or 1 o red plate (1 o rot, in German) because it is usually made of A yellow color in quadrants II & IV indicates subtraction; This is a uniaxial positive mineral with low birefringence … Access Content
OTHER ANNOUNCEMENTS
A Mineral with straight extinction in crossed polarized light (xpl) has its maximum birefringence at 45° By using an accessory plate (commonly gypsum or quartz) it is possible to artificially augment or hinder the retardation. … Access Doc
THE CALCITE EXPERIMENT
76 Examples Quartz had indices of 1.544 (ordinary ray) and 1. 553 (extraordinary ray), giving a birefringence of . Interference colors of randomly oriented quartz grains in 0.03 mm thin section range from to . A gypsum plate is an accessory … Access This Document
Petrology Lab Thin Sections Distinguishing Features Of Minerals
Chlorite is distinguished from muscovite and biotite by its green color, pleochroism, and weak birefringence. Serpentine usually has lower refractive indices and is less pleochroic. Brucite: Colorless in thin section. Brucite is most commonly mistaken for talk, micas or gypsum. … Retrieve Full Source
ESS 439 Lab 2 Isotropic Materials, Anisotropic Minerals
(iii) Describe what happens as the stage is rotated through 360° (iv) Select an olivine, rotate stage until "extinct", rotate 45°cw , insert gypsum n s-n f is called the birefringence ( δ ) and it is a function of the orientation of the mineral relative to the light path. … Doc Retrieval
Optical Mineralogy Calcite Cross-polarized Light …
Very high birefringence. cross twinning. cleavage goes in and out when state is rotated 3:55 Add to Gypsum it's in every home and you even eat it by OklahomaHorizonTV 6,977 views … View Video
Optical Microscopy – Exercise 4
Make sure you understand the relationship between the orientation of n and the elongation direction of the crystal; ∞ Is this a tabular or prismatic mineral? ∞ Using the gypsum plate to help, what is the maximum polarisation colour you can find for this mineral? ∞ What is the birefringence of … Access Doc
Semester 062 – Geol 464: Carbonate Geology – The Composition …
Recrystallization and dissolution. * ¾Petrographically, gypsum and anhydrite are easily distinguished on the basis of their optical properties: ¾Gypsum has low relief and weak birefringence and … Read Here
GYPSUM AND ANHYDRITE DEPOSITS IN SOUTHWESTERN INDIANA
In thin sections anhydrite may be distinguished from gypsum and calcite by its pseudocubic cleavage and higher birefringence. TYPES OF –GYPSUM DEPOSITS Bedded deposits Bedded deposits are the most important commercial sources of gypsum. … Get Document
Geology 2142
Birefringence and Extinction If an optic axis of an anisotropic mineral is vertical (ie parallel to the the mineral PLUS that of the plate In this case the interference colour INCREASES Example Quartz: birefringence = 0.009 nm Retardation = 270 nm First order white interference colour Gypsum … View Document
Characteristics Of Common White Pigments
1-10 microns); high birefringence with strong interference colors may fluoresce a medium purple color; reacts with acids to evolve carbon dioxide. no significant hazards Gypsum calcium sulfate dyhydrate, CaSO4. 2H2O Pigment White 25 since antiquity 2.32-2.36 1.520; 1.523; 1.530 low birefringence; euhedral shaped … Document Viewer
Chrysotile – Wikipedia, The Free Encyclopedia
Birefringence: 0.008 (max) Dispersion: relatively weak: Fusibility: dehydrates at 550–750 °C: Solubility: insoluble in water fibres degrade in dilute acid … Read Article
LAB 1: OPTICAL PROPERTIES AND THE PLM #1 Orthoscopic Light
Interference Colors and Birefringence When white light passes through an anisotropic mineral it splits into to waves that the slow direction (the same elongation direction as gypsum). • Length Fast (Negative Elongation): Crystals are elongated parallel to … Read Here
MINERALOGICAL NC S
]TINERALOGICAL NOTES! i ctilT]rdfll$l Ftc. 2 Gypsum crl.stals from Clal'ton Playa, Nevada. thick, of fibrous crystals of Iow birefringence, leading to an outer, micro-cr,vstalline la1'er, approximatel,l' 0.5 mm thick, of fibrous material of higher birefringence (Fig.3). … Retrieve Document
NOTE ON THE OCCURRENCE OF CALCIUM SULPHATE
The hemihydrate is characterized by a fibrous or prismatic habit, with indices of refraction a:1.55*, y:1.57, birefringence:0.02, parallel extinction and positive elongation. The birefringence therefore exceeds that of gypsum, but is less than that of anhydrite; the higher indices distinguish hemihydrate from gypsum, … Fetch Doc
Optical Mineralogy
For constant thickness (30 mm section) interference is proportional to birefringence (d) sensitive tint plate: quartz (gypsum or mica also used) 1. cut so that thickness adds exactly 1l to D (~ 550 nm) … Get Doc
Calcite Mine And Slot Canyon
Calcite extracted from these trenches during WWII was used in the manufacturing of Norden bombsights. Distance from downtown San Diego: 104 miles. … Read News