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Miniature portrait of Johann Georg Albrecht Höpfner (1759-1813), date and artist unknown; private collection. Burgerbiliothek Bern, Neg. 5590.
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Tremolite, Ca2(Mg,Fe)5Si8O22(OH)2, is a calcic amphibole commonly found in greenschist-facies to amphibolite-facies calc-silicate and in low-grade ultrabasic rocks. In the new IMA nomenclature of amphiboles (Leake et al., 1997) tremolite forms part of the tremolite-actinolite-ferro-actinolite series: Whereas usually the dividing line between two sp...
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New investigations on the columbite from Vishteritsa locality, Western Rhodopes have been performed in order to obtain precise data on its chemical composition and thus to determine its particular mineral species type in the light of the changes in the nomenclature and classification of the columbite group undertaken by IMA since 2007. The capabili...
Citations
... This paper will explore varieties of amphiboles from different sources to demonstrate differences between the mineralogically predetermined habit of elongate particles. We used tremolite mineral samples as one of the most representative examples of amphiboles, which occurs in a variety of habits [10][11][12]2,3,13,7]. In particular, Cavariani [14] noted that the non-asbestiform variety of tremolite is "predominant" in the earth's crust, though asbestiform tremolite can also be found "almost everywhere" in the world. ...
... The official formula from the IMA Master List for tremolite is Ca 2 It is an end member of the tremolite-ferroactinolite series. The term used is tremolite when the ratio Mg/(Mg + Fe 2+ ) ≥ 0.90, actinolite when the ratio Mg/(Mg + Fe 2+ ) is between 0.50 and 0.90, and ferroactinolite when the ratio Mg/(Mg + Fe 2+ ) < 0.50 [39,48,49]. The FT-IR results indicated that the weak reflection peak at around 3670 cm −1 is due to the bending modes of the OH group [33]. ...
Greyish-purple tremolite jade has become well known in the past few years, and the origin of its color has attracted the attention of gemologists. In this study, FT-IR spectra, EPMA, EPR spectra, micro-XRF, UV–Vis–NIR spectra, and LA-ICP-MS in situ mapping were analyzed to investigate the chromophore elements. The study sample was chosen from the Sanchahe mine, Qinghai Province, NW China, which has the typical characteristics of a gradual color change. The FT-IR and EPMA results revealed that the mineral composition of the dark and light greyish-purple regions of the sample are primarily composed of tremolite. UV–Vis–NIR spectra demonstrated that the greyish-purple color is mainly due to strong absorptions at 560 nm and 700 nm and weak absorption at 745 nm in the visible range. The EPR spectra presented ~3400 G six hyperfine lines resulting from the hyperfine interactions of the unpaired electron with the Mn2+ nucleus in the octahedral site. The UV–Vis–NIR and EPR spectra analyses demonstrated that Mn2+ is the origin of the purple color. A comparison of the major elements in the light and dark regions indicated that the chromogenic elements have strong positive correlations with Mn, Cu, and Fe. LA-ICP-MS mapping used to analyze the first transition metals indicated possible positive correlations between the greyish-purple color and the trace chromogenic elements. This suggested that the Mn, Cu, and Fe contents are significantly high in the dark band region. Combining in situ LA-ICP-MS mapping of trace elements, UV–Vis spectra, and EPR analysis results, it was suggested that Mn, Cu, and Fe are the major contributors to the greyish-purple color. This study provides a reference for the specific experimental methods to determine chromophores and the origin of color in tremolite jades.
... To address this question, thermogravimetric and differential scanning calorimetry (TG/ DSC) was used to study the thermal behavior of twelve tremolite samples from different locations. Samples were chosen because they are (1) monomineralic, (2) quarried for commercial purposes, (3) and are the subject of many important mineralogical and biomedical studies [15,[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61]. Specimens include tremolite from the following locations: San Severino Lucano (southern Italy), Val Malenco (northern Italy), Maryland (USA), Praborna (northern Italy), Monastero di Lanzo (northern Italy), Val d'Ala (northern Italy), Reventino (southern Italy), Verrayes (northern Italy), Bracchiello (northern Italy), Caprie (northern Italy), Fowler (USA), Campolungo (Switzerland). ...
... The literature data confirm our observations. Samples from San Severino, Maryland, Val Malenco, Monastero, Bracchiello, Praborna and Reventino are considered exclusively asbestiform [37, 43-45, 47-51, 56, 58, 61-68], whereas Caprie, Fowler and Campolungo samples are considered non-asbestiform (prismatic) [15,52,53,59]. Both morphologies were noted in the Verrayes and Ala samples [44,60]. ...
Tremolite asbestos is classified as a carcinogenic substance because it can cause a number of diseases when inhaled. The tremolite breakdown temperature reported in the literature varies by about 280 °C and has not been fully characterized from a thermal perspective. In order to address this gap in the scientific literature, a systematic study of the thermal behavior was conducted of twelve tremolite samples using thermogravimetric and differential scanning calorimetry (TG/DSC) supplemented by PXRD, SEM/EDS, EPMA/EDS and TEM/EDS. Tremolite samples from different locations (i.e., Italy, Switzerland and USA) were selected for their social, health, economic and industrial relevance. Data reveal that the breakdown of tremolite occurs in a temperature range of about 200 °C. The implications of this finding are discussed in light of chemical and morphological data. Variations in the breakdown temperature are mainly ascribed to the morphology of the studied tremolite samples. This study suggests that thermal analysis could be a new method for effectively distinguishing between asbestos and non-asbestos tremolite samples. The thermal oxidation of iron in the various tremolite samples occurs at different temperatures, and hence reduction of tremolite reactivity through the thermal oxidation of iron should be planned on a sample-by-sample basis. Given the different temperatures recorded for tremolite breakdown, the effectively detecting the presence of tremolite in bulk natural samples by thermal analysis can only be carried out if a thermogram of that specific sample is available. This is an important issue, especially in areas with a natural occurrence of asbestos outcrops.
Graphical Abstract
... It is an end-member of the tremoliteferroactinolite series. Term tremolite is used when the ratio Mg/(Mg + Fe 2+ ) ≥ 0.90, actinolite when the ratio Mg/(Mg + Fe 2+ ) is between 0.50 and 0.90, and ferroactinolite when the ratio Mg/(Mg + Fe 2+ ) < 0.50 [10,11]. ...
The aim of this study is to identify the infrared absorption band suitable for quantifying tremolite in three powdered samples (fine, medium, and large size classes) coming from a quarry of ophiolitic friable rocks in the western part of the Calabria region of Italy. Three IR bands were considered: OH stretching band between 3700 and 3650 cm
−1
, the stretching bands of the Si-O-Si linkage between 1200 and 900 cm
−1
, and the absorbance band at 756 cm
−1
attributable to tremolite. The amount of tremolite in the test samples was quantified by using the curve parameters of the three analytical bands. The quantitative analysis of tremolite using the band due to OH stretchings (3700–3650 cm
−1
) and the bands attributed to the Si-O-Si stretchings (1200–900 cm
−1
) showed high values for all test samples. Their use overestimated the tremolite amount because both bands were affected at the interfering mineral silicates such as talc, kaolinite, chlorite, and serpentinites. The abundant presence of antigorite in studied samples mainly in medium size class sample had a key role in our findings. The band at 756 cm
−1
was not affected at the interfering minerals and can be used for quantitative analysis of tremolite in sample coming from ophiolitic deposits.
