Tutorials – Coconino Lapidary Club

Your Slab Saw is Your Friend

Mineral Man Mel — Sun, 13 Oct 2024 00:12:47 +0000

This short tutorial on how to operate a slab saw is directed toward the new user and can be a refresher for the seasoned slab-miester.

Generally slab saws are heavy, so find a covered area indoors to place it, (or outside if you have to). You probably won’t be moving it unless yours has wheels. Because your saw uses oil as a coolant/lubricant take that into consideration when deciding where to place it. The area around the saw will be messy no matter what you do. A nearby source of electricity, good overhead lighting and a workbench next to the saw are essential for obtaining the best results.

Safety is number one when working with any type of saw. Your electric cord should be a grounded three prong plug, no bare wires showing. Depending on the size of the blade your saw uses, 12”, 14”, 16”, 18” on up to 36”, your motor size will vary accordingly. From a ½ hp to 1 ¾ hp electric motor, so if you need to use a drop cord, the bare minimum to use is a SJTW 16awg cord, the older saw motors, unless they were upgraded, will use a lot of amps just turning them on. Sometimes a saw-cut can take an hour or better to complete so using a cord that is too small for the amperage will overheat the motor and wear it out prematurely. Never leave a running saw unattended, even if it has an automatic shut-off, the moment you walk away bad things tend to happen, maybe you didn’t secure that large rock in the saw vice well enough and it moves, binding that $400.00 blade in a running motor, so it’s best to stay within 10 feet or so to prevent expensive mishaps.

So now you want to cut one of those prize rocks you found last weekend, gotta know what’s inside right ! Your saw uses oil as a lubricant or should, using water is insufficent to lubricate and keep the blade cool during cutting, I recommend NOT using water. What I do recommend is using an appropriate oil available through slab saw dealers, which will give you many options to choose from. I use a Shell Oil product, Amber Neutral Oil 100 – available in 5 gallon containers. So how much oil will I need? Just enough to cover the diamonds on the rim of the blade, on my 18” that’s 3/8 of an inch. Adding more than what covers the rim will cause unnecessary drag making the motor work harder.

My saw is a 1960’s Great Western 18” which uses about 4 gallons of oil to cover the diamonds on the rim 3/8” and a combination hydraulic feed and 15 lb weight, to pull the rock through the blade. The speed at which the rock moves through the blade is important, slow is your friend, giving a smooth cut, too fast a feed and you get hop marks making more work for your finished piece.

Depending on what type of material you are cutting, mud build-up in the pan will signal when it’s time to drain the oil. Your motor may run slower, overheat and shut off due to mud building up in the bottom of the pan. This can happen to such an extent that the saw blades’ diamond rim are in the mud. Soft materials like Onyx, Serpentine, and Howlite are ground away as the rock passes through the saw blade, creating a lot of mud.

When it’s time for an oil change, look forward to getting filthy. At this time the entire machine interior should be cleaned. My ritual is to let the machine sit idle for at least 3 days after my last cut to let the mud settle out. I next use a 5 gallon bucket, with a wire strainer I made to fit inside, and a paper grocery bag resting on that. I then drain the oil into the bag. So now there is a layer of mud at the bottom of the pan and oil above that. I pull the drain plug and let the oil drain out, the mud is heavy enough that the oil will drain right over it – now I have reclaimed 75% of the oil leaving the mud and some oil. The fun begins when it’s time to push the mud through that drain hole and do the same process with the 5 gallon bucket strainer and grocery bag. It takes 3 separate buckets and strainers on my machine, as the oil remaining suspended in the mud will gravitate out into the bucket over several weeks time, retrieving a little more oil.

USE OF CRYSTAL FORMS AND HABITS IN MINERAL IDENTIFICATION

Mineral Man Mel — Mon, 01 Feb 2021 17:32:13 +0000

The atoms within the crystal of a mineral are arranged in a regular fashion to form a lattice, and the crystal exhibits a shape with surface regularity which reflects its internal symmetry[Ref1]. The shape of a crystal is often typical of a mineral. and often typical the location where found; thus, crystal shape comprised of crystallographic forms modulated by crystal habit can be a useful tool in mineral identification.

The crystals of all minerals fall into seven families defined by their required symmetries as given in the table in Figure 1[Ref2]. The hexagonal family comprises two crystal systems as seen in Figure 1. Planes and shapes which enclose space as shown in Reference 3 are the crystallographic forms which comprise the shapes of crystals exhibited by minerals. The basic forms exhibited by the seven crystal systems are shown in Figure 2. Environmental conditions during deposition can influence the both the forms present on the crystal and the habit of a crystal in influencing its shape [Ref5].

Figure 1. The crystal families, systems, and their required symmetries[Ref2].

Figure 2. Forms of the basic prisms exhibited by the six crystal systems[Ref4].

Gallery of Crystal Systems, Forms, and Habits

In order to introduce some of the forms and habits of crystals I’ll use examples of minerals we often have enjoyed seeing in the literature and at lapidary and mineral shows as shown in Figures 3-9.

CUBIC CRYSTAL SYSTEM

Figure 3. Skeletal or hoppered crystals of galena on sphalerite, Madan Ore Field, Rhodope Mountains, Bulgaria [Ref5,8].

TETRAGONAL CRYSTAL SYSTEM

Figure4. Tabular crystal of wulfenite, Los Lamentos Mountains, Chihuahua, Mexico[Ref5,9].

ORTHORHOMBIC CRYSTAL SYSTEM

Figure 5. Acicular crystals of mesolite on green hydroxyapophylite, Pashan quarries,
Pashan Pune District, Maharashtra State, India[Ref5,10].

HEXAGONAL CRYSTAL SYSTEM

Figure 6. Bipyramidal crystals of quartz paramorph after hexagonal beta quatz, with hematite crystals, Florence Mine, Egremont, Cumbria, England, UK[Ref3,11].

Figure 7. Crystal of Beryl var. emerald displaying faces of the hexagonal and dihexagonal prisms, of the hexagonal pyramid, and of the basal pinacoid, Muzo Mine, Muso Municipality, Boyaca’ Department. Colombia[Ref3,12].

TRIGONAL CRYSTAL SYSTEM

Figure 8. Phantomed schalenohedral crystals of calcite, Mariposa Mine, Terlingua District, Brewster County, Texas[Ref 6,13]

Figure 7. Rhombohedral crystals of calcite, Gonsen Mine, St. Gallen, Switzerland[Ref3,14].

MONOCLINIC CRYSTAL SYSTEM

Figure 8. Crystal of gypsum (selenite), with faces comprising two domes and six pinacoids, Gilbralter Mine, Naica, Chihuahua, Mexico[Ref3,5,15].

TRICLINIC CRYSTAL SYSTEM

Figure 9. Crystal of Axinite-(Fe) with 7 pinacoidal faces, Pulva Mount. Tyumenskaya, Urals Region, Russia, Asia[Ref5.16].

REFERENCES

Ref 1. https://www3.nd.edu/~amoukasi/CBE30361/Lecture__crystallography_A.pdf

Ref 2. https://en.wikipedia.org/wiki/Crystal_system

Ref 3. https://www.tulane.edu/~sanelson/eens211/forms_zones_habit.htm

Ref 4. http://www.geologyin.com/2014/11/crystal-structure-and-crystal-system.html

Ref 5. https://en.wikipedia.org/wiki/Crystal_habit

Ref 6. http://www.galleries.com/minerals/property/habits.htm

Ref 7. http://www.minsocam.org/msa/collectors_corner/id/mineral_id_keyi8.htm

Ref 8. https://www.youtube.com/watch?v=f_g3r79mG9s

Ref 9. https://www.pinterest.com/pin/369506344411688204/

Ref 10. https://www.mindat.org/photo-303305.html

Ref 11. https://www.irocks.com/minerals/specimen/42517

Ref 12. https://www.rockngem.com/uncommon-emerald-exhibit-opening-sept-26/

Ref 13. https://www.spiritrockshop.com/Calcite_Mariposa.html

Ref 14. https://www.fabreminerals.com/LargePhoto.php?FILE=Calcite-SH47AB1f.jpg&LANG=EN

Ref 15. https://www.irocks.com/minerals/specimen/38370

Ref 16. https://www.crystalclassics.co.uk/product/cc19390/

USES OF CLEAVAGE, PARTING, AND FRACTURE IN MINERAL IDENTIFICATION

Mineral Man Mel — Mon, 25 Jan 2021 16:52:30 +0000

CLEAVAGE IN A MINERAL CRYSTAL[Ref1]

Cleavage in a mineral is the tendency for the crystal to split along definite crystallographic planes as exemplified by the rhombohedron cleaved from a calcite crystal shown in Figure 1[Ref1]. These planes of weakness are present within a regular repeating array of atoms and ions within the crystal and are always parallel to a potential face of the crystal. The weakness arises from the chemical bonds between cleavage planes being fewer in number or weaker than those between ions and atoms within the cleavage planes. Accordingly the crystal will tend to split between the cleavage planes and along a plane of relative weakness. When present, it is the uniqueness of the mode of cleavage in a mineral that makes it a tool in its identification.

Mineral crystals exhibit modes of cleavage along six families of planes as shown in Figure 1. Identification of the mode of cleavage and descriptions of its appearance and ease of cleaving can be used as steps in the use of Mineral Identification Keys and data compendiums as listed in References 2-7

The excellent YouTube video of Reference 2 shows how to experimentally develop and evaluate modes of cleavage, parting, and fracture in crystals in their identification. Note that use of eye protective wear is a must while performing these experiments.

Figure 1. Cleavage rhombohedron from a calcite crystal from Naica, Chihuahua, Mexico[Ref9].

Figure 1. Six families of cleavage planes exhibited by minerals[Ref10]

As demonstrations of the effects on cleavage of the density and strength of chemical bonds crossing the cleavage plane compared to the cleavage plane itself, consider its behavior in the mica family of minerals, in calcite, and in the diamond.

Cleavage in Muscovite Mica

Muscovite of the mica family, as the other members, only cleaves along planes parallel to the basal plane[Ref11] of a crystal with resulting thin sheets as shown in Figure 2. The structural relationship of the cleavage plane to the relative strengths of chemical bonds between the atoms in the lattice of the muscovite crystal is shown in Figure 3.

Figure 2. Sheets of muscovite mica parallel to the basal crystal plane[Ref12].

Figure 3. The basal plane of the muscovite crystal is parallel to the layers of potassium ions (blue) and to the intervening layers of silicon and aluminum atoms covalently bonded to oxygen atoms to form layers[Ref13]. The strengths of these covalent bonds are greatly stronger than the electrostatic attraction between the positive charges of potassium ions and the negative charges of the hydroxyl ions OH^2—on the surfaces of the layers; thus, cleavage occurs between the covalently bonded sheets, not through them.

Cleavage in Calcite

Calcite crystallizes in the trigonal crystal system[Ref15] and cleaves along six planes into rhombohedrons as shown in Figure 4.

Figure 4. Rhombohedrons with shiny flat cleaved surfaces as cleaved from a calcite crystal[Ref15].

Figure 5. Calcite cleavage rhombohedrons and lattice structure of calcite showing the relative arrangement of the calcium ions Ca²⁺ and carbonate ions CO₃^2_[Ref9] .

The angles between the legs of the rhombohedral faces are 78.5° and 101.5°.[Ref16] Note that the six cleavage planes lie between extended chain-like arrays of calcium ions and of carbonate ions, and minimal density of bonds crossing the cleavage planes.

Cleavage in Diamond

Cleavage in a diamond crystal can proceed any on of eight octahedral planes which parallel the octahedral faces of a diamond crystal as shown in Figures 6-9. The video shown in Reference 17 demonstrates cleaving of a diamond crystal and the relationship the cleavage plane to the density of bonds crossing the plane.

Figure 6. The basic cubic lattice structure of the diamond crystal with
the diagonal octahedral plane is shown in blue[Ref18].

Figure 7. View of the diamond crystal lattice showing planes with fewer
bonds crossing it lying between two parallel octahedral planes, each
with larger densities of atoms and bonds than the plane between them[Ref19].

Figure 8. View of the diamond crystal showing that cleavage occurs between the octahedral planes[Ref19].

The parallelism of both a cleavage plane and octahedral faces of a diamond crystal is shown in Figure 9. A representative perfect cleaved surface of a diamond crystal is shown in Figure 10. The white linear features are presne on the outer surface of the cleaved crystal.

Figure 9. Octahedral diamond crystal with cleavage along a plane parallel to two of
Its octahedral faces[Ref20].

Figure 10. Smooth and shiny cleavage surface of
Diamond[Ref20].

Descriptors of Cleavage for Use With Mineral Identification

In Mineral Identification Flow Charts [Ref3] and Mineral Data Tables[Ref4,5,6] not only the mode of cleavage, but descriptions of the quality and ease of cleavage for each mineral also are used as part of the body of information used in identification.

Descriptors of the quality of cleavage are summarized in the table in Figure 11. In addition the difficulty in achieving is described as easy, hard, and difficult to produce[Ref3].

Figure 11. Descriptions of cleavage used in mineral identification[Ref].

REFERENCES

Ref 1. https://en.wikipedia.org/wiki/Cleavage_(crystal)

Ref 2. .http://www.minsocam.org/msa/collectors_corner/id/mineral_id_keyi6.htm

Ref 3. http://www.minsocam.org/msa/collectors_corner/Id/mineral_id_keyi1.htm#TOC

Ref 4. www.mindat.org

Ref 5. http://webmineral.com/

Ref 6. https://www.minerals.net/MineralMain.aspx

Ref 7. Mineralogical Society of America – Mineral-Related Links

Ref 8. https://www.jstor.org/stable/30063973?seq=15#metadata_info_tab_contents

Ref 9. https://www.treasuremountainmining.com/4.3%22-Gemmy-Double-Refracting-PINK-ICELAND-SPAR-Calcite-Crystal-Mexico-for-sale

Ref 10. https://images.slideplayer.com/20/5954014/slides/slide_21.jpg

Ref 11. https://www.mindat.org/min-2815.html

Ref 12. https://www.pitt.edu/~cejones/GeoImages/1Minerals/1IgneousMineralz/Micas.html

Ref 13. https://www.semanticscholar.org/paper/How-flat-is-an-air-cleaved-mica-surface-Ostendorf-Schmitz/9138459a4a23daf157b9cfd22e08eee2aaf32087/figure/0

Ref 14. https://www.mindat.org/min-859.html

Ref 15. https://www.witchcraftsartisanalchemy.com/viking-sunstone-natural-rhombohedral-iceland-spar-optical-calcite-crystal/

Ref 16. https://chemdemos.uoregon.edu/demos/Properties-of-An-Ionic-Salt-0

Ref 17. https://www.britannica.com/science/calcite

Ref 18. https://jgs.lyellcollection.org/content/176/2/337

Ref 19 . https://vimeo.com/20281170

Ref 20. https://www.google.com/search?q=image+of+a+diamond+clevage+surface&client=firefox-b-1-d&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjS3pLQ_drtAhWSLH0KHemBBy4Q_AUoAXoECBEQAw&biw=1382&bih=911#imgrc=jAnPo_wrqLUWNM

FRACTURE IN MINERAL IDENTIFICATION

Mineral Man Mel — Fri, 22 Jan 2021 18:54:24 +0000

Fracture in mineralogy is the texture and shape of the surface formed when the mineral is fractured. Fracture differs from cleavage and parting, which involve clean splitting along a plane surface, as it produces rough irregular surfaces [Ref1]. The appearance of fracture surfaces among minerals is highly varied and is a useful tool in identification. In this part of my Blog I’ll describe the fracture surfaces broadly seen in minerals.

Conchoidal fracture is characterized by smoothly curving nested arcs as those on a seashell[Ref2].

Figure 1. Conchoidal fracture in rose quartz[Ref3,4].

Earthy fracture results in dull, clay-like surfaces without crystalline appearance[Ref2].

Figure 2. Earthy fracture in massive limonite[Ref5,6].

Fibrous fracture is typified by elongated crystal forms[Ref2].

Figure 3. Fibrous fracture in chrysotile (asbestos) [Re7,8].

Granular fracture is produced in aggregates of crystals[Ref2].

Figure 4. Granular fracture in an aggregate of arsenopyrite crystals[Ref9,10]

Hackly fracture produces torn edges and surfaces[Ref2].

Figure 5. Hackly fracture in copper producing torn edges[Ref11,12].

Irregular fracture presents an irregular fracture pattern[Ref2]

Figure 6. Plagioclase feldspar showing an irregular fracture surface[Ref13,14].

Splintery fracture produces thin long cleavages or partings[Ref 2].

Figure 7. Splintery fracture in actinolite [Ref15,16].

Uneven fracture features flat surfaces in a random pattern[Ref2].

Figure 8. Flat surfaces unevenly arrayed on blue sodalite[Ref17,18].

REFERENCES

Ref1 . https://en.wikipedia.org/wiki/Fracture_(mineralogy)

Ref 2. http://csmgeo.csm.jmu.edu/geollab/kearns/Minerals/Fracture.html

Ref 3. https://www.pinterest.com/pin/109564203407418361/

Ref 4. https://www.mindat.org/min-3337.html

Ref 5. https://en.wikipedia.org/wiki/Fracture_(mineralogy)#/media/File:Limonite_bog_iron_cm02.jpg

Ref 6. https://www.mindat.org/min-2402.html

Ref 7. https://en.wikipedia.org/wiki/Fracture_(mineralogy)

Ref 8. https://www.mindat.org/min-975.html

Ref .9 https://sanuja.com/blog/ore-minerals-and-rocks

Ref 10. https://www.mindat.org/min-305.html

Ref 11. https://geology-fundamentals.fandom.com/wiki/4241978/hackly-fracture

Ref 12. https://www.mindat.org/min-1209.html

Ref 13. http://www.pitt.edu/~cejones/GeoImages/1Minerals/1IgneousMineralz/Feldspars.html

Ref 14. http://webmin.mindat.org/data/Plagioclase.shtml#.YADaz-BlCV4

Ref 15. https://www.minerals.net/Image/2/9/Actinolite.aspx

Ref 16. https://www.mindat.org/min-18.html

Ref 17. https://www.minerals.net/mineral_glossary/uneven_fracture.aspx

Ref 18. https://www.mindat.org/min-3701.html

MINERAL STUFF: AMBER, THE GEM

Mineral Man Mel — Tue, 29 Sep 2020 17:03:00 +0000

Amber is a hard resin formed from tree sap by fossilization and is many millions of years old[Ref1]. Since Neolithic times (about 9000-3000 BC) and before the Copper Age[Ref]2) amber has been highly valued as a gemstone and used to create beautiful jewelry and artworks. Wide use of amber in Early Europe and in the area of the Mediterranean Sea is shown in jewelry and artworks displayed in Figures 2-7. Works from the Medieval Era to the present are shown in Figures 8-13.

In this Blog chemical and physical properties of amber which underlie its beauty and use as a gem are described in descriptions of its chemical and mechanical properties, and the sources of its colors. Also preservation of fossils of insects and other organisms in amber is described briefly.

AMBER IN ANCIENT EUROPE

As shown in Figure 1 amber from sites (red) where amber was found in Ancient Europe were distributed widely from their greatest concentrations along the coast of the Baltic Sea and along the North Sea coast along Jutland. As indicated by the routes indicted in black and red movement of amber could proceed from the North and Baltic Seas to Mediterranean countries terminating in what are now Italy and Greece[Ref]. Collateral routes led to the Black Sea, Syria, and Egypt[Ref3]. Amber was moved further Eastward along the Great Silk Road to China and Southeast Asia[Ref4]. Collateral routes between sites of origin over what is now Europe to the major North-South routes served to distribute locally mined amber around the continent.

Figure 1. Amber sources and trade routes in
Ancient Europe[Ref3].

AMBER JEWELRY AND ART WORKS FROM ANCIENT TIMES INTO MODERN TIMES

Figure 2.Etruscan pendant, Foreprts of a wild boar, 525-480 BC[Ref5].

Figure 3. Italic carving of horse head in profile, 500-400 BC[Ref5].

Figure 4. Italic or Etruscan necklace with carved amber scarab beetle and large carnelian beads mounted in gold, 550-=400 BC[Ref4].

Figure 5. Greek gold necklace with amber beads mounted in gold. 6^th-4th Century BC[Ref5]

Figure 7. Amber intaglio finger ring, Egypt, New Kingdom, 1550-712 BC[Ref5].

Figure 6. Roman amber amulet carved in shape of gladiator’s helmet, circa 1^st-2^nd Century AD[Ref6].

Figure 7 Roman die carved from amber, 100-200 AD[Ref5]

Figure 8. Amber Paternoster, Middel European, circa 1260 AD[Ref7].

Figure 9. Amber greyhound pendant, Czecj 1600[Ref8].

Figure 10. Amber in gold earrings, Georgian Era, 1714-1830 AD[Ref9].

Figure 11. Necklace with amber set in gold, Italian, circa 1860-1870[Ref10].

Figure 12. Egyptian Revival amber and opal necklace set in gold, Art Nouveau,
1890-1910[Ref11].

Figure13. Art Deco styled amber earrings set in Russian Silver Gold Vermeil, Recent[Ref12].

THE CHEMISTRY OF AMBER

The fossilization of tree sap into amber proceeds by crosslinking of di-terpenoid and tri-terpenoid molecules by free-radical polymerization[Ref13,14]. Over the millions of years during which crosslinking occurs to form polymers; polymerization, and cyclisation also occur resulting in new chemical compounds[Ref13,15,16]. The resulting mixture of substances can be described in terms of its carbon, hydrogen, and oxygen contents by the formula C₁₀H₁₆O_.Sulfur comprising up to 1% of chemical species may also be present[Ref].

SOURCES OF THE COLORS OF AMBER

Figure 14. Colors of Baltic amber[Ref17].

AMBER PIGMENTS

Studies[Ref18-27] on specimens of amber gathered from worldwide sources have shown that members of the chemical terpenoid family[Ref13] as well as other chemical species can contribute to the yellow to brown, red, and black colors of amber as shown by specimens of Baltic Amber in Figure 14.

As an example a study conducted on Baltic amber separation by liquid chromatography* showed separation of terpenoids and unsaturated organic compounds showed colors ranging between yellow, shades of red, and brown as shown in Tables I and II [Ref25]. These colors have been found in amber gathered from around the world.

*In separation of chemical species by liquid chromatography[Ref27] specific chemicals are used to sequester other chemical species which transport at different rates during separation by gravity resulting in degrees of separation from their collective position which range between 1.00 and 0.00 as shown by the example in Figure 15 .

Figure 15. Positions of separated chemical compounds in thin film chromatography. The positions of each is unique[Ref27].

AMBER WITH COLOR DUE TO FLUORESCENCE

Some amber from the Dominican Republic exhibits a strong Cobalt Blue fluorescenceas shown in Figure 16[Ref28]; some amber found in the Baltic, the Ukraine, Far-Eastern Russia, and Sumatra also exhibit blue fluorescence[[29,32]. Studies on these ambers have shown that the blue fluorescence in ambers from the Dominican Republic and Sumatra stems from the ring-like organic molecule perylene[Ref28,30,31] and that from the amber from Far-Eastern Russia stems from the pyrene eximer[Ref29,34,35].

Figure 16. Blue-colored amber from the Dominican Republic. The color is due to fluorescence[Ref27].

PHYSICAL PROPERIES OF AMBER

Being an organic resin amber is amorphous with no crystalline structure; accordingly it is not classified as a mineral but as a mineraloid, a mineral-like material[Ref36]. It’s Mohs Hardness is in the range 1-3 and it fractures in brittle fashion but is tough in its tenacity at temperatures near room value.[Ref36]. At

higher temperatures near210°C amber can be bent, allowing repair of amber pipe stems, as well as formed by pressing and sintering pieces together[Ref37.38]. The latter process allows construction of art objects such as a box as shown in Figure 17. [Ref39].

Figure 17. Box constructed of pressed and heated Baltic amber[Ref39].

PALEONTOLOGY OF AMBER

Organisms and organic matter such as a feather can be trapped and ultimately over long time become inclusions in amber. With initial entrapment on the surface of amber and subsequent deposit of more amber organism can be entrapped as shown in the sequence in Figures 18 and 19. A great variety of organisms can be preserved as shown in Figure . Following initial and subsequent deposits of sticky amber and entrapment episodes a volume of amber containing fossils is attained[Ref40].

Figure 18 . Organisms preserved in amber. The legend for this Figure is shown in
Figure 19 [Ref40].

Figure 19 . Legend for organisms in Figure 18. {Ref40].

REFERENCES: AMBER

Ref 1. https://en.wikipedia.org/wiki/Amber

Ref 2. https://www.ancient.eu/Amber/

Ref 3. https://commons.wikimedia.org/wiki/File:Amber_sources_in_Europe.jpg

Ref 4. https://en.wikipedia.org/wiki/Amber_Road

Ref 5. http://museumcatalogues.getty.edu/amber/objects/37/

Ref 6. https://www.pinterest.com/pin/373869206562406397/

Ref 7. https://www.pinterest.com/pin/438397344957150618/

Ref 8. http://shewhoworshipscarlin.tumblr.com/post/134242133432/greyhound-pendant-1600

Ref 9. https://www.1stdibs.com/jewelry/earrings/dangle-earrings/georgian-amber-gold-earrings/id-j_202058/