The doleritic bluestone monoliths at Stonehenge have long been known to have been sourced from the Mynydd Preseli area in west Wales, some 225 km away. On geochemical grounds, based on a range of major and trace elements determined by laboratory-based X-ray fluorescence spectrometry, they have been divided into three groups (Groups 1–3). Subsequently, rare earth element data obtained by solution nebulization ICP-MS showed Group 2 Stone 45 to have been sourced from Cerrigmarchogion with Group 2 Stone 62 showing similarities to the outcrops of Carn Ddafad-las and Garn Ddu Fach. In order to test this possible link, portable XRF (pXRF) analyses were obtained in situ from Stone 62 at Stonehenge and from key outcrops in the Preseli.

To obtain reliable results from heterogeneous coarse-grained igneous rocks using pXRF to enable comparisons between orthostats and possible sources, a robust analytical strategy was developed. For outcrops this involved a series of horizontal traverses through individual outcrops comprising 10 to 15 analyses a few centimetres apart, giving 60–175 independent analyses per outcrop. This gives a large, analysed surface area per outcrop providing representative data and also has potential to show any vertical variation in source outcrops. Analyses were taken from similarly weathered surfaces on orthostats and outcrops to minimise compositional changes from surface weathering, and a minimum of 20 analyses were taken from orthostats at various locations across the stone. This approach provides a set of well-determined elements which can reliably be used for provenance studies (including K, Fe, Mn, Zn, Rb, Sr, Zr, Nb, Ba). Nickel, Ti and V are affected slightly more by weathering but still prove useful in comparisons, but Cr, used in earlier studies as a compositional discriminant with Ni, here has poor accuracy by pXRF and is not used.

The pXRF analyses show that Stone 62 sits within the same ‘compositional space’ (for multiple element concentrations and ranges) as analyses from Carn Ddafad-las and Garn Ddu Fach, two outcrops of the same intrusion which differ from all other analysed outcrops. More specifically, analyses from Stone 62 and Garn Ddu Fach overlap, these forming a subset of the analyses from Carn Ddafad-las, which shows a more extensive range of those same elements. On this basis it is suggested that Garn Ddu Fach is the likely source of Stonehenge non-spotted dolerite Stone 62, a suggestion supported by indistinguishable petrographic characteristics between Stone 62 and dolerite sample PGDF24 from Garn Ddu Fach.

众所周知，巨石阵的玄武岩青石巨石来自威尔士西部约 225 公里外的 Mynydd Preseli 地区。在地球化学方面，基于实验室 X 射线荧光光谱法确定的一系列主要元素和微量元素，它们被分为三组（第 1-3 组）。随后，通过溶液雾化 ICP-MS 获得的稀土元素数据显示，第 2 组 Stone 45 来自 Cerrigmarchogion，第 2 组 Stone 62 与 Carn Ddafad-las 和 Garn Ddu Fach 的露头相似。为了测试这种可能的联系，便携式 XRF (pXRF) 分析从巨石阵的 62 号石头和 Preseli 的主要露头中进行了原位分析。

为了使用 pXRF 从非均质粗粒火成岩中获得可靠的结果，以便能够比较原位元和可能的来源，开发了一种稳健的分析策略。对于露头，这涉及通过单个露头的一系列水平遍历，包括相隔几厘米的 10 到 15 次分析，每个露头进行 60-175 次独立分析。这为每个露头提供了一个大的分析表面积，提供了具有代表性的数据，并且还有可能显示源露头的任何垂直变化。分析是从直立器和露头上类似风化的表面进行的，以尽量减少表面风化造成的成分变化，并且至少从石头不同位置的直立器进行了 20 次分析。这种方法提供了一组确定的元素，可以可靠地用于来源研究（包括 K、Fe、Mn、Zn、Rb、Sr、Zr、Nb、Ba）。镍、钛和钒受风化影响稍大，但在比较中仍然证明是有用的，但在早期研究中用作与镍的成分鉴别的铬在 pXRF 中的准确性较差，因此未使用。

pXRF 分析表明，Stone 62 与 Carn Ddafad-las 和 Garn Ddu Fach 的分析位于相同的“组成空间”（针对多种元素浓度和范围），这两个露头是同一侵入体的两个露头，与所有其他分析的露头不同。更具体地说，Stone 62 和 Garn Ddu Fach 的分析重叠，这些构成 Carn Ddafad-las 分析的一个子集，显示了这些相同元素的更广泛范围。在此基础上，建议 Garn Ddu Fach 可能是巨石阵无斑点辉绿岩 62 号石的来源，这一建议得到了来自 Garn Ddu Fach 的 62 号石和辉绿岩样品 PGDF24 之间难以区分的岩相特征的支持。