Determination of the Rare Mineral Faustite and Mineralogy of the Grasshopper Claim

Neil Ray, West Texas Analytical Laboratory, Geochemist & Mineralogist

Faustite is a very rare mineral, essentially the zinc analogue of turquoise.  Typically, turquoise contains an average of 6% copper, zinc can almost entirely replace copper for the allocation to faustite.  Faustite’s rarity is due to its limited geological occurrence, typically found in clay rich shales affected by copper rich hydrothermal fluids.  A great deal of speculation arises on the existence of faustite in green colored turquoise from various mining districts.  The coloration of most green Nevada turquoise is due to amounts of iron 3+ and the lesser-known chromophore vanadium.  This discussion will examine turquoise and the occurrence of faustite from a few well-known mining claims, as well as one that is likely lesser known, but none the less the incredible and rare Grasshopper Claim.  

Background on Testing Methods

P3M software was developed over the course of 10 years that uses major and minor trace element chemistry to calculate mineral percents in various rock types, compiling 100 different mineral species.  The software uses complex algorithms that assign elements to minerals based on lithology and associated calculated pressure/temperature conditions.  There are a lot of laboratory methods to acquire a chemical analysis on a whole rock, the standard method is to grind the sample and digest it in strong acids by weight and analyze it on an instrument known as an ICP-OES, which stands for inductively coupled plasma optical emission spectrometer.  Though ICP is certainly the most accurate method available with the possibility to analyze almost every element on the periodic table, it is simply not feasible for precious materials.  The next method that is widely used is xray fluorescence, which is non-destructive and reliable for elements from magnesium to uranium.  Unfortunately, it does not detect lighter elements, such as sodium which is very important for mineralogical determinations.  To overcome sodium, an algorithm was developed to calculate sodium based on major element allocations.  Additionally, it is also important to distinguish between iron 2+ and iron 3+, which also an xrf analyzer cannot achieve, thus an additional algorithm was developed to differentiate between both forms of iron.  Finally, though lithium concentrations are very low in turquoise a final algorithm was developed to determine lithium concentrations for lithium exploration of pegmatites.  These algorithms have been tested on material analyzed by ICP as well as chemical titration and verified on over 40 published peer reviewed papers containing chemical analyses of various rock types, with over an 85% accuracy.  The major and minor elements are used to calculate the reported 100 mineral species, again verified by peer reviewed published data or additional laboratory analyses.   Most of the minerals that are reported are not found in turquoise, only becoming more important in the examination of other rock types such as igneous and metamorphic rocks.  Mineralogical determination is invaluable as to determine mineralogy in rocks, a separate instrument known as an xrd, xray diffraction, is required, which too is destructive.

Since an xrf is used to determine elements, it is important to select the correct analyzer, that has a large detector capable of measuring the bare minimum of magnesium and light elements such as silicon and aluminum.  It is also equally important to select an analyzer with the proper modes, such as both mining and soil mode.  Soil mode alone will not be appropriate due to analyzing whole rock and not ground fines.  Prior to analysis, it would be ideal to grind the sample, however once again this is not an option for precious materials.  Rocks are complex, especially hydrothermal which can show a myriad of mineralization in the same rock, which I will elaborate on in just a bit.  The greatest capability of P3M is an algorithm that uses a database of turquoise from over 55+ mines to calculate a probability of origin.  Provenance is one of the most important aspects of turquoise, if known, greatly increasing the value of the specimen.  In ideal conditions someone would purchase the stone from the miner directly or from someone who purchased it directly from the miner with a proper trail of provenance, unfortunately this seldom happens.  Most vintage jewelry and cabochons produced many years ago have little to no documentation on origin and it becomes a “guessing game” often posted to forums and social media.  As I mentioned rocks are complex and to use the trace element chemistry to determine origin as a fingerprint is a complex task indeed, since so much variation can exist in the same specimen.  Such an analysis can’t be completed by comparing an element in one sample from one mine to the same element in another sample from a different mine, such a linear approach is not effective at all.  Geochemists utilize what is called a ternary diagram, which allows for three variables to be compared against each other at once.  Even though a chemical analysis can vary in spots within the same rock, the ratio of these three elements remains consistent, which allows them to be plotted on a triangle diagram in a distinct region or field.  Considering the complexity and overlap of the many mines, several ternary diagrams of many elements must be constructed to identify regions and eliminate outliers and overlap.  The identification of turquoise origin also can not be completed without a proper database of known provenance, I was fortunate enough to have Mike Ryan with Turquoise in America lend his extensive Callais collection to build a comprehensive database, as well as Shreve Saville who owns the Thunder Mountain claim and interests in the Grasshopper claim to aid in submitting material as well.  The Grasshopper claim is what I would like to discuss as we explore the occurrence and rarity of faustite. 

Analyzing for Faustite, the Mines and Specimens

Carico Lake Specimens: top (#1), right (#2), and bottom (#3)

As I previously mentioned faustite is very rare and it is assumed that the classic green material from Carico Lake is faustite bearing, however the specimens analyzed in this discussion has little to no zinc.  More specimens of Carico Lake will be analyzed soon to determine the zinc content and faustite.  These specimens show a considerably low zinc content, surprisingly Lander Blue and Lone Mountain have higher amounts of zinc than these three specimens, but again they represent only a small population of Carico Lake material.  One noted Carico Lake specimen is variscite and the classic green coloration is indeed caused by a combination of iron and vanadium.  The occurrence of vanadium in turquoise is well documented in the literature, but it is ultimately a lesser-known chromophore in green turquoise, particularly noted here in the examined Carico Lake specimens.  The table that follows below is an analysis performed on three specimens from the Callais collection, notice zinc is less than 500 ppm or 0.05% in all three specimens.  Additionally, note that specimen #1 has low copper and is almost entirely composed of variscite with a low turquoise content and minor chalcosiderite.  Specimen #2 is composed almost entirely of turquoise and represents the rarer blue material found at Carico Lake, and specimen #3 is quartz rich turquoise with intricate webbing.  The corresponding low zinc concentration yields no faustite on all three analyzed specimens.  The mineralogy is summarized below, omitting minerals that are non-existent from the P3M calculation.   

	Carico Lake #1	Carico Lake #2	Carico Lake #3
Quartz	1.00	3.07	16.75
Anorthite	-----	-----	0.78
Albite	-----	-----	1.80
Orthoclase	6.41	0.73	2.18
Magnesiochromite	0.04	0.01	0.09
Ilmenite	-----	-----	0.21
Hematite	-----	0.41	0.28
Rutile	0.02	0.04	0.11
Zircon	0.01	-----	0.02
Turquoise	10.11	92.15	63.11
Chalcosiderite	1.82	-----	-----
Variscite	73.09	-----	-----
Faustite	-----	-----	-----
Ankerite	1.74	0.28	0.85
Rhodochrosite	-----	0.01	0.06
Azurite/Malachite	1.31	0.29	1.22
Halite	0.11	0.35	0.44
Fluorite	-----	0.02	0.04
Pyrite	4.33	0.26	2.84
Illite/Clays	-----	1.89	9.09
Chalcopyrite	-----	0.02	0.02
Bornite	-----	0.05	0.03
Arsenopyrite	-----	0.42	-----
Galena	-----	-----	0.04
Scheelite	-----	-----	0.04
Pyrolusite	0.01	-----	-----

	Carico Lake #1	Carico Lake #2	Carico Lake #3
SiO2	4.82	4.45	8.25
Al2O3	41.33	29.66	35.39
MgO	1.57	1.60	1.50
CaO	1.98	0.20	1.51
K2O	0.85	0.13	0.15
Na2O	0.12	0.12	0.12
P2O5	28.85	26.64	28.54
TiO2	0.02	0.04	0.05
MnO	0.01	0.01	0.01
FeO	0.62	0.13	0.04
Fe2O3	0.01	1.39	0.39
S	1.81	0.17	0.64
Cl	0.05	0.19	0.10
Trace Elements (ppm wt.)
Strontium	687	22	698
Barium	2165	1659	6425
Rubidium	13	5	9
Zirconium	44	3	68
Molybdenum	10	29	5
Vanadium	1465	34	1690
Nickel	45	28	67
Copper	6178	73331	20630
Zinc	198	420	367
Chromium	259	109	314
Lead	5	6	162
Arsenic	14	1955	12
Tungsten	37	97	111
Antimony	17	29	23
Tin	9	18	8
Silver	6	14	7
Bismuth	5	4	6
Niobium	12	3	7
Uranium	39	25	35
Thorium	2	3	2
Lithium	0.05	0.02	0.11

    Orvil Jack

Orvil Jack Specimen for Analyses (#1 & #2)

Similarly, lets examine Orvil Jack, which contains a significant amount of zinc and faustite and see how it compares to Carico Lake.  One large specimen of Orvil Jack from the Callais collection was analyzed on two separate spots for mineralogical determination.  The first spot analyzed was the classic bluish apple green color and the second spot is the paler coloration.  The Orvil Jack specimen analyzed is considerably different from Carico Lake specimens, being composed of variscite and faustite, with only minor turquoise.  It is noted that Carico Lake #1 resembles Orvil Jack slightly in that it too is composed of variscite, however it has more chalcosiderite and lacks faustite.  Below is the mineralogy of the two spots analyzed on the Orvil Jack rough, again omitting minerals that are non-existent in the P3M calculation.        

	Orvil Jack Bluish Apple Green	Orvil Jack Paler matrix
Orthoclase	-----	1.22
Magnesiochromite	0.03	0.02
Hematite	0.14	0.15
Rutile	0.03	0.03
Turquoise	7.64	5.66
Chalcosiderite	0.08	0.10
Variscite	62.90	85.51
Faustite	27.00	5.36
Ankerite	0.39	0.52
Rhodochrosite	0.02	0.01
Azurite/Malachite	0.48	0.50
Halite	0.13	0.22
Fluorite	0.01	0.01
Pyrite	0.31	0.30
Chlorite/Serpentine	0.74	0.32
Uraninite	0.03	0.04
Scheelite	0.07	0.03

It can be observed from the analyses that Orvil Jack has a much simpler mineralogy than Carico Lake containing no additional copper sulfide mineralization and no quartz.  It can also be noted that the mineralogy is consistent for both analyses, except for the major turquoise group minerals that vary.  Such consistency is why the trace element ternary diagrams are useful in origin determination.  What is interesting about the Orvil Jack is that it is very high in uranium with uranium concentrations exceeding 200 ppm or 0.02%, which may be weakly detectable on a Geiger counter.  This elevated uranium concentrations would consider Orvil Jack as a moderate grade uranium ore.  Note the exceptional high concentrations of zinc at 22897 and 7261 ppm, 2.28% and 0.73%, which are 20 to 100x greater than that of the Carico Lake specimens analyzed, attaining to its faustite content.     

	Orvil Jack Bluish Apple Green	Orvil Jack Paler matrix
SiO2	0.39	2.44
Al2O3	36.69	34.54
MgO	1.38	1.51
CaO	0.55	0.68
K2O	0.23	0.20
Na2O	0.12	0.12
P2O5	31.29	38.72
TiO2	0.03	0.03
MnO	0.01	0.01
FeO	0.04	0.04
Fe2O3	0.46	0.49
S	0.17	0.15
Cl	0.07	0.11
Trace Elements (ppm wt.)
Strontium	221	315
Barium	2177	1694
Rubidium	43	53
Zirconium	3	6
Molybdenum	57	110
Vanadium	661	1051
Nickel	313	93
Copper	6033	4234
Zinc	22897	7261
Chromium	218	179
Lead	4	4
Arsenic	4	13
Tungsten	457	213
Antimony	27	8
Tin	16	7
Silver	12	6
Bismuth	5	5
Niobium	18	29
Uranium	221	278
Thorium	2	2
Lithium	0.04	0.57

 Grasshopper

Finally, I would like to focus the discussion on a lesser-known claim known as Grasshopper.  Shreve Saville submitted five extraordinary samples of Grasshopper cabochons.  You can see from the photo that Grasshopper shows a considerable variation in matrix patterns and coloration, ranging from dark green to apple green, blue green, and even polychrome matrix patterns.  

Grasshopper Specimens: top from left to right (#1-#3), bottom left (#4), and bottom right (#5)

Grasshopper is very similar to the Carico Lake specimens that were analyzed in that it has high concentrations of vanadium, which again acts as a chromophore yielding a dark green color.  However, unlike the Carico Lake specimens that were analyzed, Grasshopper lacks chalcosiderite and variscite and contains rare faustite.  The mineralogical compositions vary considerably, as only the apple green is faustite bearing.  Grasshopper shows a higher faustite content than Orvil Jack and significantly more turquoise, coupled with the absence of variscite.

	Grasshopper #1	Grasshopper #2	Grasshopper #3	Grasshopper #4	Grasshopper #4
Quartz	32.54	1.54	7.69	15.32	2.97
Anorthite	-----	-----	-----	-----	0.79
Albite	-----	6.07	5.09	3.54	3.35
Orthoclase	1.86	0.51	0.96	3.72	1.73
Magnesiochromite	0.15	-----	-----	-----	0.18
Chromite	-----	0.02	0.02	0.02	-----
Ilmenite	-----	-----	-----	-----	0.07
Magnetite	-----	0.45	-----	-----	-----
Hematite	2.04	1.59	3.43	2.12	1.07
Rutile	0.04	-----	-----	-----	0.04
Zircon	-----	-----	-----	0.01	-----
Turquoise	54.41	88.13	78.01	69.59	46.06
Chalcosiderite	-----	-----	-----	-----	-----
Variscite	-----	-----	-----	-----	-----
Faustite	-----	-----	-----	-----	42.19
Ankerite	3.55	-----	-----	-----	-----
Rhodochrosite	0.04	0.02	-----	-----	0.02
Azurite/Malachite	0.07	0.03	-----	-----	0.22
Halite	0.31	0.17	0.10	0.09	0.09
Fluorite	0.01	0.01	-----	-----	-----
Pyrite	4.79	0.43	0.51	0.80	1.06
Illite/Clays	-----	-----	-----	2.18	-----
Chalcopyrite	-----	0.01	-----	-----	-----
Bornite	0.04	0.07	-----	-----	0.02
Arsenopyrite	0.07	0.03	-----	-----	0.03
Wolframite	-----	0.01	-----	-----	-----
Scheelite	0.08	0.01	0.02	0.03	0.11
Limonite/Goethite	-----	0.90	4.16	2.56	-----
Pyrolusite	-----	-----	0.01	0.02	-----

Specimen #1 shows a beautiful polychrome matted matrix with dual dark green and light blue coloration.  The matrix is black chert and the variation in the turquoise color is due to the amount of substituted iron 3+, yielding multi-color blue and green coloration.  Specimen #2 is considerably different as it is entirely light blue with intricate spider webbing, attaining the highest turquoise content of the five specimens that were analyzed.  Specimen #3 is very similar to specimen #1 with a dark green matted matrix, however it has less quartz and a higher turquoise content.  This specimen also has a considerably higher iron content with notably more limonite and hematite, occurring as matrix webbing and dark green inclusions that can be seen as halos around the edge.  Specimen #4 represents the classic green turquoise look with a moderate quartz content and consequently the only specimen analyzed that contains appreciable clays.  Finally, the specimen of interest is specimen #5 that is noticeably different in appearance with an apple green coloration and the only specimen analyzed that contains faustite with a concentration of 42%, coupled with almost an equal amount of turquoise.  It is noted that specimen #5 has a zinc concentration of 37854 ppm, which is almost 4% zinc.  Though the five specimens are somewhat like the analyzed Carico Lake specimens, they are considerably unique in that they lack variscite and chalcosiderite and have a higher quartz content, coupled with significantly more iron that yields the intricate hematite and limonite webbing observed in the five specimens that were analyzed.

	Grasshopper #1	Grasshopper #2	Grasshopper #3	Grasshopper #4	Grasshopper #4
SiO2	23.68	6.60	9.56	16.47	6.51
Al2O3	38.86	41.92	46.77	39.21	42.77
MgO	1.60	2.10	2.22	2.08	2.08
CaO	0.79	0.78	1.21	1.35	0.95
K2O	0.21	0.07	0.14	0.51	0.22
Na2O	0.77	0.75	0.58	0.66	0.35
P2O5	17.62	29.92	28.38	24.45	30.05
TiO2	0.02	0.01	0.02	0.13	0.03
MnO	0.01	0.01	0.01	0.01	0.01
FeO	0.99	0.66	1.64	1.34	0.30
Fe2O3	4.65	5.62	12.62	7.54	2.68
S	1.77	0.22	0.23	0.35	0.44
Cl	0.11	0.08	0.05	0.04	0.04
Trace Elements (ppm wt.)
Strontium	181	244	277	527	206
Barium	2665	4202	2210	2971	6775
Rubidium	13	9	5	20	8
Zirconium	19	6	7	41	5
Molybdenum	35	10	7	55	12
Vanadium	2083	813	718	2005	6313
Nickel	154	919	439	46	80
Copper	29064	58990	50738	43696	27064
Zinc	6394	4944	3148	6473	37854
Chromium	791	416	445	355	1041
Lead	13	27	34	56	9
Arsenic	214	104	65	62	120
Tungsten	358	121	110	136	546
Antimony	33	18	26	19	25
Tin	9	22	18	22	13
Silver	8	10	15	11	19
Bismuth	6	6	6	7	6
Niobium	6	5	4	4	3
Uranium	56	53	40	24	41
Thorium	3	3	3	4	3
Lithium	0.05	0.02	0.03	0.00	0.00

 Formation Characteristics

Now that we have identified the mineralogical differences and similarities between the classic mines of Carico Lake and Orvil Jack and how they compare to Grasshopper, lets examine the formational characteristics and why Orvil Jack contains variscite and faustite, where Grasshopper contains turquoise and faustite, but no variscite.  Variscite is typically a low pressure/temperature mineral formed as a product of supergene alteration, as seen in Carico Lake #1, which is predominately variscite that formed at near atmospheric conditions.  The formation of faustite requires higher temperatures, driven by hydrothermal metal rich fluids, with particularly an excess of zinc.  Some of the Carico Lake specimens fall in the temperature range, like Orvil Jack, for the formation of faustite, however the lack of zinc restricts faustite mineralization.  It is important to note that the dataset presented here is restricted to three samples and that additional samples analyzed would likely show zinc and faustite, considering it falls in the ideal temperature and pressure conditions for faustite mineralization.  The Orvil Jack specimen that was analyzed formed at a higher temperature, but it is still notably lower than the analyzed Grasshopper specimens, and the Orvil Jack is barely considered mesothermal in mineralization.  The analyzed Grasshopper specimens has the highest formation temperature of the three mine sets that were analyzed, which explains the absence of variscite and the dominance of turquoise.  It should also be mentioned that Grasshopper has a significant amount of chromium and nickel, which are typically constituents derived from the mantle.  Possible mantle derived magmatic fluids are evidenced by a temperature more than 300C. 

Conclusion  

The analyzed Grasshopper is a very unique and high-quality turquoise that is unlike the analyzed Carico Lake and Orvil Jack counterparts.  Though it shares some similarities to the Carico Lake and Orvil Jack specimens that were analyzed, it is absent of variscite and contains more faustite.  Though the Orvil Jack specimen contains faustite as well, it is coupled with variscite.  It appears that the Grasshopper specimens compared to the analyzed Carico Lake and Orvil Jack specimens have a unique mineralogy of faustite and turquoise alone.  If you are interested in purchasing cabochons of this remarkable gem, which I recommend you do so while they last, please contact Shreve Saville by visiting his website: turquoisedeluxe.com.  Special thanks to Shreve for submitting these fine specimens for analysis, as well as additional material to further this research.  It should be noted that more specimens of Carico Lake and Orvil Jack will be added for analyses soon as I continue the research on the coveted mineral faustite.  If you don’t have Carico Lake or Orvil Jack in your collection, it is recommended to add some as both materials are becoming rare and difficult to obtain with each passing day.  

This study was made possible by material lent from the Callais collection, courtesy of Mike Ryan with Turquoise in America.  If you had not yet purchased the three additions, it is highly recommended that you reserve your copy.  A considerable amount of work and detail went into the book set to provide the unique history of turquoise.  Mike is an excellent historian, and you will certainly learn a considerable amount of detail about turquoise as it transcends time from the very early days of mining to the present.

West Texas Analytical Laboratory is not affiliated with Turquoise in America or any of Shreve Saville’s mining claims and nor does it receive economic compensation for promotion from either and nor does either receive compensation for the promotion of the lab.  This collective collaboration is simply made possible for the love of turquoise.  I am a geochemist with over 15 years laboratory experience and graduate level research on metasomatic and hydrothermal emplacement.  If you are interested in submitting samples for analysis, you may contact West Texas Laboratory at 580-977-6951.  The cost is $65 for a comprehensive analysis that includes mineralogy, origin, grade, and more or $35 for a simple chemical analysis to identify if it is turquoise and natural or treated.